A228449 a(n) = floor(n! / 4^n).

1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 3, 9, 28, 92, 324, 1217, 4871, 20703, 93166, 442542, 2212711, 11616735, 63892044, 367379253, 2204275523, 13776722023, 89548693155, 604453678799, 4231175751597, 30676024199079, 230070181493096, 1783043906571497, 14264351252571976

Offset: 0

Author

Alex Ratushnyak, Oct 27 2013

Keywords

• nonn
• less

Crossrefs

Cf. A000142, A066979, A212310.

Programs

Mathematica

Table[Floor[n!/4^n],{n,0,40}] (* Harvey P. Dale, Jun 07 2014 *)

Python

import math
for n in range(99): print(math.factorial(n)//(4**n), end=', ')