A091760 a(n) = 0^n + 3*((n+2)^n/(n+3) - (-1)^n/(n+3)).

1, 3, 9, 63, 555, 6303, 87381, 1434891, 27272727, 589486923, 14288622513, 384034370151, 11338782475059, 364911575317383, 12716046006693165, 477070508584969299, 19174662804725408175, 822058028667720327891, 37449142857142857142857, 1806613178226958108033743

Offset

0,2

Links

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

Formula

a(n) ~ 3 * e^2 * n^(n-1). - Amiram Eldar, Jan 23 2026

Mathematica

a[n_] := 3*((n+2)^n - (-1)^n) / (n+3); a[0] = 1; Array[a, 20, 0] (* Amiram Eldar, Jan 23 2026 *)

Crossrefs

Cf. A083063.

Sequence in context: A108557 A109285 A245165 * A144525 A276535 A228776

Adjacent sequences: A091757 A091758 A091759 * A091761 A091762 A091763

Keyword

easy,nonn

Author

Paul Barry, Feb 03 2004

Extensions

More terms from Amiram Eldar, Jan 23 2026

Status

approved