A085880 → x ↦ x/(x+1)

OEIS matches ?

• A005159: row sums, 15 terms agree OEIS nonn (row-sum match: finite agreement only) · view at the OEIS · generated b-file 200 terms from n = 0 ?
• A151383: row sums, 15 terms agree OEIS nonn (row-sum match: finite agreement only) · view at the OEIS · generated b-file 200 terms from n = 0 ?

A generated b-file is computed from the node's definition along the row alignment of its OEIS link and starts at the entry's offset. It is an identification on a finite prefix, not a proof that the node and the OEIS entry agree for every n.

OEIS submission text ?

Fields to paste into an OEIS submission: the example %e, the formula %F and programs %t (Mathematica) and %o (PARI/GP) that list the same rows. For an OEIS link the row numbers, the offset and the orientation are those of the entry, as matched; the matched terms were compared with the published ones, which identifies the node with the entry on a finite prefix, not for every n. The PARI/GP program is not machine-checked here.

Triangle begins:
   1:    1;
   2:    1,     2;
   3:    2,     8,      8;
   4:    5,    30,     60,      40;
   5:   14,   112,    336,     448,     224;
   6:   42,   420,   1680,    3360,    3360,     1344;
   7:  132,  1584,   7920,   21120,   31680,    25344,     8448;
   8:  429,  6006,  36036,  120120,  240240,   288288,   192192,    54912;
   9: 1430, 22880, 160160,  640640, 1601600,  2562560,  2562560,  1464320,   366080;
  10: 4862, 87516, 700128, 3267264, 9801792, 19603584, 26138112, 22404096, 11202048, 2489344;

The row polynomials satisfy (n+n*x)*P(n,x) = (4*n-6+(12*n-18)*x+(8*n-12)*x^2)*P(n-1,x) for n >= 2, with P(1,x) = 1.

P[1, x_] := 1;
P[n_, x_] := P[n, x] = Expand[Together[((4*n - 6 + (12*n - 18)*x + (8*n - 12)*x^2)*P[n - 1, x])/(n + n*x)]];
Table[CoefficientList[P[n, x], x], {n, 1, 10}] // Flatten

P(N) = {my(v = vector(N)); v[1] = 1; for(n = 2, N, my(i = n); v[i] = ((4*n - 6 + (12*n - 18)*x + (8*n - 12)*x^2)*v[i - 1])/(n + n*x)); v};
row(n, p) = {my(c = Vecrev(p)); c};
T(N) = {my(v = P(N)); concat(vector(#v, i, row(i, v[i])))};
T(10)

Proved properties

• Real-rooted. Every row P_n, n >= 1, is zero or real-rooted with all roots in [-1, 0]
  Every polynomial of the sequence has only real roots, inside the stated interval.
  by the cited steps: e-e1834b9d49e58efd
• Coefficients of one sign. Every nonzero row, n >= 1: the coefficients of P_n have one sign
  All coefficients of each polynomial have the same sign (after x -> -x when alternating).
  derived from the cited steps by a stated theorem: e-e1834b9d49e58efd
• Hadamard kernel (Malo). Rows P_n, n >= 1, are Hadamard kernels (preserve real-rootedness)
  Multiplying the coefficients of any real-rooted polynomial termwise by those of a row (Hadamard product) gives a real-rooted polynomial again.
  derived from the cited steps by a stated theorem: e-e1834b9d49e58efd

Proof chains

1 incoming proof step. Each step is expanded back to the roots of the proof DAG, the theorem checks of a node's own rule. JSON

• preserver_image mobius, shift 0 e-e1834b9d49e58efd

  Affine, reversal and Möbius substitutions (elementary) polytool ?

  • premise (sequence): Triangle T(n,k) read by rows: multiply row n of Pascal's triangle (A007318) by the n-th Catalan number (A000108).
    uses: Every row P_n, n >= 1, is zero or real-rooted with all roots in (-inf, 0]
    • theorem_check liu_wang e-68a5cf53bdad0f8f root: theorem check

      Liu–Wang theorem [LW07, Thm 2.1, Cor 2.4] ?

    • preserver_image reversal, shift 0 e-93440eb5a87a1e1b

      Affine, reversal and Möbius substitutions (elementary) polytool ?

      • premise (sequence): Triangle T(n,k) read by rows: multiply row n of Pascal's triangle (A007318) by the n-th Catalan number (A000108).
        uses: Every row P_n, n >= 1, is zero or real-rooted with all roots in (-inf, 0]
        • ↵ theorem_check liu_wang e-68a5cf53bdad0f8f (expanded above)

Related sequences ?

Same fingerprint (67)

Equal up to content, sign, reversal and a small index shift.

• A120910 → D
• A344565 → basis A007318
• A007318 → ×(1+(3/2)n+(1/2)n²) → x ↦ x/(x+1)
• A038208 → basis A013611
• A356546 → basis A007318
• basis-map coefficients of A113214, shifted → basis A013611
• A007318 → ×(−(1/2)n+(1/2)n²) → x ↦ x+1
• A120910: Triangle read by rows: T(n,k) is the number of ternary words of length n having k levels (n >= 1, 0 <= k <= n-…
• A038208 → basis A007318
• A038338 → basis A007318
• basis-map coefficients of A026729 → basis A013609
• A135838 → basis A013611
• A028326 → basis A013611
• A013609: Triangle of coefficients in expansion of (1+2*x)^n.
• A038330 → basis A013609
• A135838 → x ↦ x/(x+1)
• A196347 → basis A013611
• A007318 → ×(1+2n+n²) → x ↦ x+1
• A159854 → x ↦ x/(x+1)
• A038207 → D
• A178821 → basis A013611
• A038325 → basis A013611
• A038207: Triangle whose (i,j)-th entry is binomial(i,j)*2^(i-j).
• A356546 → basis A013611
• basis-map coefficients of A112227 → basis A013609
• basis-map coefficients of A021012 → basis A013609
• A178821 → x ↦ x/(x+1)
• A085880 → x ↦ x+1
• A007318 → ×(−(1/2)n+(1/2)n²) → x ↦ x/(x+1)
• A178822 → x ↦ x/(x+1)
• A085880 → basis A013611
• A120909: Triangle read by rows: T(n,k) is the number of ternary words of length n having k runs (i.e., subwords of maxi…
• A028326 → x ↦ x/(x+1)
• A038243 → basis A013610
• A038221 → basis A013611
• A156992 → basis A013611
• A178822 → basis A013611
• A178820 → x ↦ x/(x+1)
• A120909 → basis A013610
• A007318 → ×(1+(3/2)n+(1/2)n²) → x ↦ x+1
• A344565 → basis A013611
• A156992 → basis A007318
• A028326 → basis A007318
• A038338 → basis A013611
• A007318 → ×(1+2n+n²) → x ↦ x/(x+1)
• basis-map coefficients of A026729, shifted → basis A013609
• A085881 → basis A007318
• A027466 → basis A013611
• A196347 → basis A007318
• A120909 → D
• A038325 → basis A007318
• A344565 → x ↦ x/(x+1)
• A178821 → basis A007318
• A178820 → basis A013611
• A013609 → basis A013610
• basis-map coefficients of A113214, shifted → x ↦ x/(x+1)
• A178822 → x ↦ x+1
• A136572 → basis A013609
• A007318 → D → x ↦ x/(x+1)
• basis-map coefficients of A030528, shifted → basis A013609
• basis-map coefficients of A113214, shifted → x ↦ x+1
• A038208 → x ↦ x/(x+1)
• A135838 → x ↦ x+1
• A013609 → D
• A085881 → basis A013611
• A130123 → basis A013609
• A178820 → basis A007318

References

1. [LW07] Lily L. Liu and Yi Wang. A unified approach to polynomial sequences with only real zeros. Advances in Applied Mathematics, 38(4):542–560, May 2007. doi:10.1016/j.aam.2006.02.003