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v[1] = 1; for(n = 1, N, my(i = n + 1); v[i] = ((1 - (3*n - 7)*x + (2*n^2 - 15*n + 18)*x^2 + (6*n^2 - 27*n + 23)*x^3 + (6*n^2 - 21*n + 15)*x^4 + (2*n^2 - 6*n + 4)*x^5)*v[i - 1] + (5*x - (4*n - 26)*x^2 - (16*n - 56)*x^3 - (24*n - 62)*x^4 - (16*n - 35)*x^5 - (4*n - 8)*x^6)*deriv(v[i - 1], x) + (2*x^2 + 10*x^3 + 20*x^4 + 20*x^5 + 10*x^6 + 2*x^7)*deriv(deriv(v[i - 1], x), x))/(1 + 2*x + x^2)); v};\nrow(n, p) = {my(c = Vecrev(p)); c};\nT(N) = {my(v = P(N)); concat(vector(#v, i, row(i - 1, v[i])))};\nT(9)","reading":{"first_row":0,"offset":0,"reversed":false,"trim_zeros":"none","regular_triangle":false}}],"derivation":{"root":"n-0b0f0dd4d2c8eb05","steps":["x \u21a6 x/(x+1)"],"edges":["e-5251b6f7a7c60e6c"],"text":"A166961 \u2192 x \u21a6 x/(x+1)"},"headline":"A166961 \u2192 x \u21a6 x/(x+1)","chain":null}