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 A111778 #9 Aug 11 2025 14:01:38
%S A111778 1,20,315,4620,67830,1020600,15961050,260706600,4461170175,
%T A111778 80002622700,1503527550525,29583578524500,608837350621500,
%U A111778 13088359506222000,293538127312930500,6858722586405690000,166752692881988338125
%N A111778 Fifth column (m=4) of unsigned triangle A111595.
%F A111778 E.g.f. (1/sqrt(1-x^2))*((x/(1-x))^4)/4!.
%F A111778 a(n)=(n!/4!)*sum(binomial(2*k, k)*binomial(n-2*k-1, 3)/(4^k), k=0..floor((n-4)/2)), n>=4.
%F A111778 D-finite with recurrence (-n+4)*a(n) +4*n*a(n-1) +n*(n-1)^2*a(n-2)=0. - _R. J. Mathar_, Jun 08 2016
%t A111778 With[{nn=30},Drop[CoefficientList[Series[1/Sqrt[1-x^2] (x/(1-x))^4/4!,{x,0,nn}],x] Range[0,nn]!,4]] (* _Harvey P. Dale_, Apr 05 2015 *)
%K A111778 nonn,easy
%O A111778 4,2
%A A111778 _Wolfdieter Lang_, Aug 23 2005