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 A377888 #9 Nov 11 2024 06:45:56
%S A377888 1,2,17,289,7541,267041,11974645,650666731,41560476809,3052145052433,
%T A377888 253400719220801,23470964805942083,2399562226994185885,
%U A377888 268404500411311273465,32606551238103342068717,4275233840499570086190331,601753408713140793660643985,90500525005651471292191270433
%N A377888 E.g.f. A(x) satisfies A(x) = exp(x * A(x))/(1 - x*A(x)^2).
%F A377888 a(n) = n! * Sum_{k=0..n} (2*n-k+1)^(k-1) * binomial(3*n-2*k,n-k)/k!.
%o A377888 (PARI) a(n) = n!*sum(k=0, n, (2*n-k+1)^(k-1)*binomial(3*n-2*k, n-k)/k!);
%Y A377888 Cf. A352410, A377831, A377889.
%Y A377888 Cf. A371318.
%K A377888 nonn
%O A377888 0,2
%A A377888 _Seiichi Manyama_, Nov 10 2024