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 A379997 #9 Jan 08 2025 05:47:38
%S A379997 1,0,6,22,224,2138,25732,351846,5458224,94441042,1803255404,
%T A379997 37652268014,853321021192,20858236815258,546941712302052,
%U A379997 15313467390967222,455933682027961184,14383416438784605602,479254037890010238172,16817855455956128823486,619953003446894086537656
%N A379997 Expansion of e.g.f. 1/(exp(x) - x*exp(2*x))^2.
%F A379997 E.g.f.: B(x)^2, where B(x) is the e.g.f. of A092148.
%F A379997 a(n) = n! * Sum_{k=0..n} (k+1) * (k-2)^(n-k)/(n-k)!.
%o A379997 (PARI) a(n) = n!*sum(k=0, n, (k+1)*(k-2)^(n-k)/(n-k)!);
%Y A379997 Cf. A358738, A377529, A379933, A379992.
%Y A379997 Cf. A092148.
%K A379997 nonn,easy
%O A379997 0,3
%A A379997 _Seiichi Manyama_, Jan 07 2025