A178820 → x ↦ x/(x+1)

OEIS matches ?

• A036216: 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:
  0:   1;
  1:   4,    8;
  2:  10,   40,    40;
  3:  20,  120,   240,    160;
  4:  35,  280,   840,   1120,    560;
  5:  56,  560,  2240,   4480,   4480,   1792;
  6:  84, 1008,  5040,  13440,  20160,  16128,    5376;
  7: 120, 1680, 10080,  33600,  67200,  80640,   53760,   15360;
  8: 165, 2640, 18480,  73920, 184800, 295680,  295680,  168960,  42240;
  9: 220, 3960, 31680, 147840, 443520, 887040, 1182720, 1013760, 506880, 112640;

The row polynomials satisfy (n+n*x)*P(n,x) = (n+3+(3*n+9)*x+(2*n+6)*x^2)*P(n-1,x) for n >= 1, with P(0,x) = 1.

P[0, x_] := 1;
P[n_, x_] := P[n, x] = Expand[Together[((n + 3 + (3*n + 9)*x + (2*n + 6)*x^2)*P[n - 1, x])/(n + n*x)]];
Table[CoefficientList[P[n, x], x], {n, 0, 9}] // Flatten

P(N) = {my(v = vector(N + 1)); v[1] = 1; for(n = 1, N, my(i = n + 1); v[i] = ((n + 3 + (3*n + 9)*x + (2*n + 6)*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 - 1, v[i])))};
T(9)

Proved properties

• Real-rooted. Every row P_n, n >= 0, 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-384d0b9c26a615c7
• Coefficients of one sign. Every nonzero row, n >= 0: 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-384d0b9c26a615c7
• Hadamard kernel (Malo). Rows P_n, n >= 0, 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-384d0b9c26a615c7

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-384d0b9c26a615c7

  Affine, reversal and Möbius substitutions (elementary) polytool ?

  • premise (sequence): Triangle read by rows: T(n,k) = C(n+3,3) * C(n,k), 0 <= k <= n.
    uses: Every row P_n, n >= 0, is zero or real-rooted with all roots in (-inf, 0]
    • theorem_check liu_wang e-387009a21707feb6 root: theorem check

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

    • preserver_image reversal, shift 0 e-17b3b03bdb024482

      Affine, reversal and Möbius substitutions (elementary) polytool ?

      • premise (sequence): Triangle read by rows: T(n,k) = C(n+3,3) * C(n,k), 0 <= k <= n.
        uses: Every row P_n, n >= 0, is zero or real-rooted with all roots in (-inf, 0]
        • ↵ theorem_check liu_wang e-387009a21707feb6 (expanded above)

Related sequences ?

Same fingerprint (67)

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

• A038207: Triangle whose (i,j)-th entry is binomial(i,j)*2^(i-j).
• A038330 → basis A013609
• A135838 → x ↦ x/(x+1)
• basis-map coefficients of A021012 → basis A013609
• A028326 → basis A013611
• A038325 → basis A007318
• A013609: Triangle of coefficients in expansion of (1+2*x)^n.
• A136572 → basis A013609
• A007318 → ×(1+(3/2)n+(1/2)n²) → x ↦ x/(x+1)
• A120910 → D
• A007318 → D → x ↦ x/(x+1)
• A038208 → basis A013611
• A135838 → basis A013611
• A135838 → x ↦ x+1
• A038243 → basis A013610
• basis-map coefficients of A113214, shifted → x ↦ x+1
• 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…
• A344565 → basis A007318
• A085881 → basis A007318
• A120909 → D
• A178822 → x ↦ x+1
• A178821 → basis A007318
• basis-map coefficients of A026729 → basis A013609
• A178820 → basis A013611
• A013609 → basis A013610
• A085880 → x ↦ x/(x+1)
• A178822 → basis A013611
• A013609 → D
• A178821 → x ↦ x/(x+1)
• basis-map coefficients of A113214, shifted → basis A013611
• A028326 → x ↦ x/(x+1)
• A007318 → ×(1+(3/2)n+(1/2)n²) → x ↦ x+1
• basis-map coefficients of A030528, shifted → basis A013609
• basis-map coefficients of A026729, shifted → basis A013609
• A120909 → basis A013610
• A196347 → basis A007318
• A156992 → basis A013611
• A085881 → basis A013611
• A130123 → basis A013609
• A196347 → basis A013611
• A085880 → basis A013611
• A344565 → basis A013611
• A007318 → ×(1+2n+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-…
• A038338 → basis A013611
• A007318 → ×(−(1/2)n+(1/2)n²) → x ↦ x+1
• A028326 → basis A007318
• A038338 → basis A007318
• A038325 → basis A013611
• A159854 → x ↦ x/(x+1)
• A178822 → x ↦ x/(x+1)
• basis-map coefficients of A112227 → basis A013609
• A038207 → D
• A356546 → basis A013611
• A178821 → basis A013611
• basis-map coefficients of A113214, shifted → x ↦ x/(x+1)
• A344565 → x ↦ x/(x+1)
• A038208 → x ↦ x/(x+1)
• A085880 → x ↦ x+1
• A038221 → basis A013611
• A156992 → basis A007318
• A178820 → basis A007318
• A007318 → ×(1+2n+n²) → x ↦ x/(x+1)
• A007318 → ×(−(1/2)n+(1/2)n²) → x ↦ x/(x+1)
• A038208 → basis A007318
• A027466 → basis A013611
• A356546 → 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