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 A379685 #8 Dec 30 2024 04:28:25
%S A379685 1,3,30,551,15028,547717,25068058,1383323517,89443699176,
%T A379685 6634682537993,555501170856934,51828125728865257,5332620999430989244,
%U A379685 599894268098223894525,73253745510185331985842,9650159930850877102454693,1364228585624978795929566928,206008264557747708717576118417
%N A379685 Expansion of e.g.f. (1/x) * Series_Reversion( x * exp(-2*x) * (1 - x*exp(x)) ).
%F A379685 a(n) = (1/(n+1)) * Sum_{k=0..n} (3*n-k+2)^k * (2*n-k)!/(k! * (n-k)!).
%o A379685 (PARI) a(n) = sum(k=0, n, (3*n-k+2)^k*(2*n-k)!/(k!*(n-k)!))/(n+1);
%Y A379685 Cf. A213644, A377890, A379684.
%K A379685 nonn
%O A379685 0,2
%A A379685 _Seiichi Manyama_, Dec 29 2024