A379992 Expansion of e.g.f. exp(-3*x)/(exp(-x) - x)^2.

1, 1, 7, 41, 349, 3539, 42451, 585605, 9130297, 158692679, 3041499871, 63712004729, 1447946191957, 35479218963083, 932326476195115, 26153289728300909, 779995883104560241, 24644267406802467215, 822278654588440803511, 28891372907012629446881

Offset

0,3

Links

Table of n, a(n) for n=0..19.

Formula

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

Prog

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

Crossrefs

Cf. A358738, A377529, A379933, A379997.

Cf. A368266, A377530, A379994.

Sequence in context: A353992 A181441 A290044 * A209113 A146991 A377347

Adjacent sequences: A379983 A379990 A379991 * A379993 A379994 A379995

Keyword

nonn,easy,new

Author

Seiichi Manyama, Jan 07 2025

Status

approved