This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A331816 #11 Apr 09 2020 22:02:24
%S A331816 1,0,0,1,0,-2,0,0,1,2,0,0,-6,0,0,1,0,0,20,0,0,-12,0,0,1,0,-40,0,0,80,
%T A331816 0,0,-20,0,0,1,40,0,0,-360,0,0,220,0,0,-30,0,0,1,0,0,1120,0,0,-1680,0,
%U A331816 0,490,0,0,-42,0,0,1,0,-2240,0,0,9520,0,0,-5600,0,0,952,0,0,-56,0,0,1
%N A331816 Irregular triangle (read by rows) of coefficients T(n,k) of polynomials p(n,x) = Sum_{k=0..2*n} T(n,k) * x^k = (-1)^n * e^(x^3/3) * (((d/dx)^n) e^(-x^3/3)) for n >= 0 and 0 <= k <= 2*n.
%C A331816 Let r(s;n,x) = Sum_{k=0..s*n} A(s;n,k)*x^k = (-1)^n * e^(x^(s+1)/(s+1)) * (((d/dx)^n) e^(-x^(s+1)/(s+1))) for n >= 0 and x complex and some fixed integer s >= 1. Special cases: A(1;n,k) = A066325(n,k) and A(2;n,k) is this triangle. Formula: A(s;n,k) = (Sum_{i=0..floor(k/(s+1))} (-1)^i * binomial((n+k) /(s+1),i) * binomial(n+k-(s+1)*i,n)) * (-1)^(n-(n+k)/(s+1)) * (n!) / ((s+1)^((n+k)/(s+1)) * (((n+k)/(s+1))!)) if (n+k) mod (s+1) = 0 else 0 with n >= 0 and 0 <= k <= s*n.
%C A331816 Recurrence: (1) A(s;n,k) = A(s;n-1,k-s) - (k+1) * A(s;n-1,k+1),
%C A331816 (2) r(s;n,x) = x^s * r(s;n-1,x) - ((d/dx) r(s;n-1,x)) for n > 0 with initial values A(s;0,0) = 1 = r(s;0,x) and A(s;n,k) = 0 if k < 0 or k > s*n or (n+k) mod (s+1) > 0;
%C A331816 E.g.f.: Sum_{n>=0} r(s;n,x)*t^n/(n!) = e^((x^(s+1)-(x-t)^(s+1))/(s+1)).
%C A331816 This generalization is result of a long and intensive discussion with Wolfdieter Lang. For more information see A091752.
%F A331816 T(n,k) = (-1)^k * (n!) * (Sum_{i=0..floor(k/3)} (-1)^i * binomial((n+k) /3,i) * binomial(n+k-3*i,n)) / (3^((n+k)/3) * ((n+k)/3)!) if (n+k) mod 3 = 0 else 0 with n >= 0 and 0 <= k <= 2*n.
%F A331816 Recurrence: (1) T(n,k) = T(n-1,k-2) - (k+1) * T(n-1,k+1),
%F A331816 (2) T(n,k) = T(n-1,k-2) - 2*(n-1)*T(n-2,k-1) + (n-1)*(n-2)*T(n-3,k),
%F A331816 (3) k*T(n,k) = 2*n*T(n-1,k-2) - n*(n-1)*T(n-2,k-1),
%F A331816 (4) p(n,x) = x^2 * p(n-1,x) - (d/dx) p(n-1,x),
%F A331816 (5) p(n,x) = x^2*p(n-1,x) - 2*(n-1)*x*p(n-2,x) + (n-1)*(n-2)*p(n-3,x),
%F A331816 (6) (d/dx) p(n,x) = 2*n*x*p(n-1,x) - n*(n-1)*p(n-2,x) for n > 0 with initial values T(0,0) = 1 = p(0,x) and T(n,k) = 0 if k < 0 or k > 2*n or (n+k) mod 3 > 0.
%F A331816 T(n,2*n) = 1 for n >= 0.
%F A331816 T(3*n,0) = -T(3*n-1,1) = 2*T(3*n-2,2) = ((3*n)!)/(3^n * (n!)) for n > 0.
%F A331816 The polynomials p(n,x) satisfy for n >= 0 and x complex the differential equation: 0 = (((d/dx)^3) p(n,x)) - 2*x^2*(((d/dx)^2) p(n,x)) + (x^4 + 2*(n-1)*x) * ((d/dx) p(n,x)) - (2*n*x^3-(n+3)*n) * p(n,x).
%F A331816 E.g.f.: Sum_{n>=0} p(n,x)*t^n/(n!) = e^((x^3-(x-t)^3)/3).
%F A331816 ((d/dx)^m) p(n,x) = Sum_{i=0..m} (-1)^i * binomial(m,i) * p(m-i,-x) * p(n+i,x) for m,n >= 0 and x complex.
%F A331816 T(3*n-k,k) = A091752(n+1,k+2) for 0 <= k <= 2*n.
%F A331816 (-1)^(n-k) * T(n,3*k-n) = A049404(n,k) for n > 0 and (n+2)/3 <= k <= n.
%e A331816 The irregular triangle T(n,k) starts:
%e A331816 n\k: 0 1 2 3 4 5 6 7 8 9 10 . . . 16
%e A331816 ========================================================================
%e A331816 0 : 1
%e A331816 1 : 0 0 1
%e A331816 2 : 0 -2 0 0 1
%e A331816 3 : 2 0 0 -6 0 0 1
%e A331816 4 : 0 0 20 0 0 -12 0 0 1
%e A331816 5 : 0 -40 0 0 80 0 0 -20 0 0 1
%e A331816 6 : 40 0 0 -360 0 0 220 0 0 -30 0 0 1
%e A331816 7 : 0 0 1120 0 0 -1680 0 0 490 0 0 -42 0 0 1
%e A331816 8 : 0 -2240 0 0 9520 0 0 -5600 0 0 952 0 0 -56 0 0 1
%e A331816 etc.
%Y A331816 Cf. A049404, A066325, A091752.
%Y A331816 Row sums are (-1)^n*A252284(n).
%K A331816 sign,tabf
%O A331816 0,6
%A A331816 _Werner Schulte_, Jan 27 2020