A377685 - OEIS

%I #13 Nov 04 2024 09:09:01

%S 1,0,4,6,136,900,16308,229320,4691104,99156960,2481162480,67862678400,

%T 2063842827264,68473763804160,2468786906210688,96048626176339200,

%U 4010912604492410880,178968539487145282560,8496991445958129576960,427734144995749047152640

%N E.g.f. satisfies A(x) = (1 - x * log(1 - x*A(x)))^2.

%F E.g.f.: B(x)^2, where B(x) is the e.g.f. of A371227.

%F a(n) = 2 * n! * Sum_{k=0..floor(n/2)} (2*n-2*k+1)! * |Stirling1(n-k,k)|/( (n-k)! * (2*n-3*k+2)! ).

%o (PARI) a(n) = 2*n!*sum(k=0, n\2, (2*n-2*k+1)!*abs(stirling(n-k, k, 1))/((n-k)!*(2*n-3*k+2)!));

%Y Cf. A371117, A377686.

%Y Cf. A371227, A377390.

%K nonn

%O 0,3

%A _Seiichi Manyama_, Nov 04 2024