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 A092469 #14 Oct 30 2021 09:42:46 %S A092469 1,1,13,91,1081,10606,181189,2025325,38378449,548523856,10811257051, %T A092469 176339404099,3828413138785,68734868302738,1590128353317001, %U A092469 31543123841374681,768191679788034529,16494997547298477340 %N A092469 a(n) = Sum_{i+j+k=n, 0<=i<=j<=k<=n} (n+2j)!/(i! * (3j)! * k!). %H A092469 Vaclav Kotesovec, <a href="/A092469/b092469.txt">Table of n, a(n) for n = 0..500</a> (terms 0..200 from Seiichi Manyama) %o A092469 (PARI) a(n)=sum(i=0,n,sum(j=0,i,sum(k=0,j,if(i+j+k-n,0,(n+2*j)!/i!/(2*j)!/k!)))) %Y A092469 Cf. A092468. %K A092469 nonn %O A092469 0,3 %A A092469 _Benoit Cloitre_, Mar 25 2004