A379992 - OEIS

%I #10 Jan 08 2025 05:46:36

%S 1,1,7,41,349,3539,42451,585605,9130297,158692679,3041499871,

%T 63712004729,1447946191957,35479218963083,932326476195115,

%U 26153289728300909,779995883104560241,24644267406802467215,822278654588440803511,28891372907012629446881

%N Expansion of e.g.f. exp(-3*x)/(exp(-x) - x)^2.

%F a(n) = n! * Sum_{k=0..n} (k+1) * (k-1)^(n-k)/(n-k)!.

%o (PARI) a(n) = n!*sum(k=0, n, (k+1)*(k-1)^(n-k)/(n-k)!);

%Y Cf. A358738, A377529, A379933, A379997.

%Y Cf. A368266, A377530, A379994.

%K nonn,easy

%O 0,3

%A _Seiichi Manyama_, Jan 07 2025