A216628 a(n) = A163085(n)/n!.

1, 1, 1, 2, 3, 18, 60, 1200, 10500, 735000, 18522000, 4667544000, 359400888000, 332086420512000, 81408613942656000, 279394363051195392000, 224737840779305293440000, 2892376010829659126572800000, 7812628980363223707442752000000, 379850021025259936655866602240000000

Offset

0,4

Links

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

Prog

(Sage)
def A216628(n):
    swing = lambda n: factorial(n)/factorial(n//2)^2
    A163085 = lambda n: mul(swing(i) for i in (0..n))
    return A163085(n)/factorial(n)
[A216628(n) for n in (0..19)]

Crossrefs

Cf. A056040.

Sequence in context: A347429 A211867 A003693 * A048047 A114165 A166510

Adjacent sequences: A216625 A216626 A216627 * A216629 A216630 A216631

Keyword

nonn

Author

Peter Luschny, Sep 18 2012

Status

approved