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 A387342 #14 Aug 28 2025 11:45:38
%S A387342 1,21,280,3024,28854,253638,2103024,16689816,128014887,955485531,
%T A387342 6974119152,49965080256,352366829724,2451595670748,16858071545664,
%U A387342 114737706591984,773866620578205,5177539121330961,34391021091689416,226956883258736400,1488970185631858930
%N A387342 Expansion of 1/(1 - 6*x + x^2)^(7/2).
%H A387342 Vincenzo Librandi, <a href="/A387342/b387342.txt">Table of n, a(n) for n = 0..800</a>
%F A387342 n*a(n) = 3*(2*n+5)*a(n-1) - (n+5)*a(n-2) for n > 1.
%F A387342 a(n) = (binomial(n+6,3)/20) * A387338(n).
%F A387342 a(n) = (-1)^n * Sum_{k=0..n} (1/6)^(n-2*k) * binomial(-7/2,k) * binomial(k,n-k).
%t A387342 CoefficientList[Series[1/(1-6*x+x^2)^(7/2),{x,0,33}],x] (* _Vincenzo Librandi_, Aug 28 2025 *)
%o A387342 (PARI) my(N=30, x='x+O('x^N)); Vec(1/(1-6*x+x^2)^(7/2))
%o A387342 (Magma) R<x> := PowerSeriesRing(Rationals(), 34); f := 1/(1 - 6*x + x^2)^(7/2); coeffs := [ Coefficient(f, n) : n in [0..33] ]; coeffs; // _Vincenzo Librandi_, Aug 28 2025
%Y A387342 Cf. A387338.
%K A387342 nonn,new
%O A387342 0,2
%A A387342 _Seiichi Manyama_, Aug 27 2025