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 A357662 #11 Oct 08 2022 08:33:03
%S A357662 1,0,3,27,198,1485,12825,132678,1582497,20603727,284290560,4132840239,
%T A357662 63571690485,1038868740000,18022911716439,330305863479615,
%U A357662 6355242571945878,127721845479277737,2672729031195365949,58142565625982730462,1313557910179640120061
%N A357662 Expansion of e.g.f. cosh( (exp(3*x) - 1)/sqrt(3) ).
%F A357662 a(n) = Sum_{k=0..floor(n/2)} 3^(n-k) * Stirling2(n,2*k).
%o A357662 (PARI) my(N=30, x='x+O('x^N)); apply(round, Vec(serlaplace(cosh((exp(3*x)-1)/sqrt(3)))))
%o A357662 (PARI) a(n) = sum(k=0, n\2, 3^(n-k)*stirling(n, 2*k, 2));
%Y A357662 Cf. A024430, A357661, A357663.
%Y A357662 Cf. A357615, A357649, A357665.
%K A357662 nonn
%O A357662 0,3
%A A357662 _Seiichi Manyama_, Oct 07 2022