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 A209426 #7 Oct 26 2024 04:21:56
%S A209426 1,3,347,10707908,72078431500368,103279205595241909409817,
%T A209426 32276238007289208146779304321387283,
%U A209426 2246642168097747174860193404728752903216792387572,35410884110668229233891981980646482609768612036854978171150794831
%N A209426 Central terms of triangle A209424.
%o A209426 (PARI) {a(n)=polcoeff(polcoeff(exp(sum(m=1,2*n,x^m/m*sum(k=0,m,binomial(m,k)^m*y^k))+x*O(x^(2*n))),2*n,x),n,y)}
%o A209426 for(n=0,10,print1(a(n),", "))
%Y A209426 Cf. A209424, A209425.
%K A209426 nonn
%O A209426 0,2
%A A209426 _Paul D. Hanna_, Mar 08 2012