A065955 a(n) = floor((-1)^n*n!*(E(n,2)-E(n,1)*E(n-1,1))) where E(n,x) = Sum_{k=0..n} (-1)^k*x^k/k!.

1, 1, 2, 3, 5, 8, 14, 26, 47, 86, 159, 295, 551, 1032, 1940, 3662, 6935, 13170, 25075, 47853, 91514, 175351, 336586, 647131, 1246069, 2402690, 4638908, 8967211, 17353537, 33618332, 65191862, 126535913, 245818070, 477938269, 929968028, 1810857390, 3528610689, 6880357955

Offset

0,3

Links

Table of n, a(n) for n=0..37.

Example

1, 1, 2, 3, 5, 17/2, 89/6, 211/8, 1903/40, 62473/720, ...

Mathematica

e[n_, x_]:=Sum[(-x)^k/k!, {k, 0, n}]; a[n_]:=Floor[(-1)^n*n!*(e[n, 2]-e[n, 1]e[n-1, 1])]; Array[a, 38, 0] (* Stefano Spezia, Apr 12 2024 *)

Crossrefs

Cf. A065952, A065953, A065954, A065956.

Sequence in context: A173282 A178833 A212657 * A196118 A104880 A152478

Adjacent sequences: A065952 A065953 A065954 * A065956 A065957 A065958

Keyword

nonn

Author

N. J. A. Sloane, Dec 08 2001

Extensions

a(0)=1 prepended by and a(35)-a(37) from Stefano Spezia, Apr 12 2024

Status

approved