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 A379690 #9 Dec 30 2024 04:28:01
%S A379690 1,1,8,102,1952,49920,1603392,62100304,2818386944,146748098304,
%T A379690 8624885719040,564885716972544,40800979548180480,3222148806557544448,
%U A379690 276214603877715378176,25544721442331112192000,2535168741071076287971328,268757182971129822376624128,30311086789573678207758237696
%N A379690 Expansion of e.g.f. (1/x) * Series_Reversion( x * (1 - x*exp(2*x)) ).
%F A379690 a(n) = (1/(n+1)) * Sum_{k=0..n} (2*n-2*k)^k * (2*n-k)!/(k! * (n-k)!).
%o A379690 (PARI) a(n) = sum(k=0, n, (2*n-2*k)^k * (2*n-k)!/(k!*(n-k)!))/(n+1);
%Y A379690 Cf. A379661, A379689, A379691.
%K A379690 nonn
%O A379690 0,3
%A A379690 _Seiichi Manyama_, Dec 29 2024