%I #8 Aug 19 2023 19:05:12
%S 1,1,6,70,1242,29766,901108,33007500,1419955260,70189326748,
%T 3920638941576,244244850932424,16790688671875000,1262666306235233160,
%U 103110586277262570672,9086730135842989237456,859557307380692050631952,86872483166310571406250000
%N E.g.f. satisfies A(x) = exp(x * A(x)^2 * (1 + x/2 * A(x)^2)).
%F a(n) = n! * Sum_{k=0..n} (1/2)^(n-k) * (2*n+1)^(k-1) * binomial(k,n-k)/k!.
%o (PARI) a(n) = n!*sum(k=0, n, (1/2)^(n-k)*(2*n+1)^(k-1)*binomial(k, n-k)/k!);
%Y Cf. A091485, A365058.
%Y C. A363358.
%K nonn
%O 0,3
%A _Seiichi Manyama_, Aug 19 2023