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 A379691 #9 Dec 30 2024 04:27:55
%S A379691 1,2,17,274,6597,212736,8624581,421843472,24185705417,1591194859264,
%T A379691 118184516071641,9782950785024000,893132377427288653,
%U A379691 89156432069922504704,9661304014254414999821,1129505503357457643206656,141711496280128816909982097,18992404410135723679211716608
%N A379691 Expansion of e.g.f. (1/x) * Series_Reversion( x * exp(-x) * (1 - x*exp(2*x)) ).
%F A379691 a(n) = (1/(n+1)) * Sum_{k=0..n} (3*n-2*k+1)^k * (2*n-k)!/(k! * (n-k)!).
%o A379691 (PARI) a(n) = sum(k=0, n, (3*n-2*k+1)^k * (2*n-k)!/(k!*(n-k)!))/(n+1);
%Y A379691 Cf. A379661, A379689, A379690.
%K A379691 nonn
%O A379691 0,2
%A A379691 _Seiichi Manyama_, Dec 29 2024