A006548 (2*n)!-Sum ((-1)^(i+1)*binomial(n,i)*2^i*(2*n-1)!,i=1..n).

0, 24, 480, 40320, 2903040, 479001600, 74724249600, 20922789888000, 5690998849536000, 2432902008176640000, 1021818843434188800000, 620448401733239439360000, 372269041039943663616000000

Offset

1,2

Links

Table of n, a(n) for n=1..13.

Formula

4*floor(n/2) * (2n-1)!. - Ralf Stephan, Mar 08 2004

Prog

(PARI) a(n)=n\2*4*(2*n-1)! \\ Charles R Greathouse IV, Sep 26 2025

Crossrefs

Sequence in context: A052715 A052725 A360517 * A159877 A319426 A275041

Adjacent sequences: A006545 A006546 A006547 * A006549 A006550 A006551

Keyword

nonn

Author

N. J. A. Sloane

Status

approved