A349270 a(n) = Sum_{k=0..n} (n - k)! * k! / floor(k / 2)!^2, row sums of A349269.

1, 2, 5, 16, 46, 204, 986, 6400, 48094, 420140, 4112822, 44575584, 528787260, 6811260792, 94637153172, 1410542965248, 22446384533142, 379801729831500, 6808478318116238, 128895044005636960, 2569653423591937156, 53808349548318974312, 1180737041228428129580

Offset

0,2

Links

Seiichi Manyama, Table of n, a(n) for n = 0..449

Mathematica

Table[Sum[(n-k)!  k! / Floor[k/2]!^2, {k, 0, n}], {n, 0, 22}] (* Stefano Spezia, Nov 13 2021 *)

Prog

(PARI) a(n) = sum(k=0, n, (n - k)!*k!/(k\2)!^2); \\ Michel Marcus, Nov 13 2021

Crossrefs

Cf. A349269.

Sequence in context: A306504 A148376 A148377 * A163865 A148378 A148379

Adjacent sequences: A349267 A349268 A349269 * A349271 A349272 A349273

Keyword

nonn

Author

Peter Luschny, Nov 13 2021

Status

approved