A163087 Product{k|n} k$. Here '$' denotes the swinging factorial function (A056040).

1, 1, 2, 6, 12, 30, 240, 140, 840, 3780, 15120, 2772, 221760, 12012, 960960, 9266400, 10810800, 218790, 7351344000, 923780, 16761064320, 3259095840, 3910915008, 16224936, 41977154419200, 2028117000, 249864014400

Offset

0,3

Links

Table of n, a(n) for n=0..26.

Peter Luschny, Swinging Primes.

Example

The set of positive divisors of 3 is {1,3}. Thus a(3) = 1$ * 3$ = 1 * 6 = 6.

Maple

a := proc(n) local i; mul(i, i=map(swing, numtheory[divisors](n))) end:

Mathematica

sf[n_] := With[{f = Floor[n/2]}, Pochhammer[f+1, n-f]/f!]; a[0] = 1; a[n_] := Product[sf[k], {k, Divisors[n]}]; Table[a[n], {n, 0, 26}] (* Jean-François Alcover, Jul 26 2013 *)

Crossrefs

Cf. A098710, A163088, A163089.

Sequence in context: A080372 A335287 A322804 * A332654 A000650 A304961

Adjacent sequences: A163084 A163085 A163086 * A163088 A163089 A163090

Keyword

nonn

Author

Peter Luschny, Jul 21 2009

Status

approved