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 A351892 #11 Feb 21 2025 05:59:22
%S A351892 1,1,1,4,13,40,205,952,4921,31168,189145,1318528,9843781,74869888,
%T A351892 632536933,5475991552,49996774897,485393809408,4829958877105,
%U A351892 50858117779456,554544498995965,6259096187060224,73822470722135293,894846287081242624,11261265009125680681,146272258394568687616
%N A351892 Expansion of e.g.f. exp( sinh(sqrt(3)*x) / sqrt(3) ).
%F A351892 a(0) = 1; a(n) = Sum_{k=0..floor((n-1)/2)} binomial(n-1,2*k) * 3^k * a(n-2*k-1).
%F A351892 a(n) = Sum_{k=0..n} 3^((n-k)/2) * A136630(n,k). - _Seiichi Manyama_, Feb 20 2025
%t A351892 nmax = 25; CoefficientList[Series[Exp[Sinh[Sqrt[3] x]/Sqrt[3]], {x, 0, nmax}], x] Range[0, nmax]!
%t A351892 a[0] = 1; a[n_] := a[n] = Sum[Binomial[n - 1, 2 k] 3^k a[n - 2 k - 1], {k, 0, Floor[(n - 1)/2]}]; Table[a[n], {n, 0, 25}]
%Y A351892 Cf. A003724, A009229, A136630, A247452, A351891, A381277.
%K A351892 nonn
%O A351892 0,4
%A A351892 _Ilya Gutkovskiy_, Feb 24 2022