OFFSET
0,3
LINKS
Peter Luschny, Swinging Primes.
EXAMPLE
The set of positive divisors of 3 is {1,3}. Thus a(3) = 1$ * 3$ = 1 * 6 = 6.
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 *)
PROG
(SageMath)
def swing(n: int) -> int: return factorial(n) // factorial(n // 2) ** 2
def a(n: int) -> int: return prod(swing(k) for k in divisors(n)) if n > 0 else 1
print([a(n) for n in range(27)]) # Peter Luschny, Sep 22 2025
CROSSREFS
KEYWORD
nonn
AUTHOR
Peter Luschny, Jul 21 2009
EXTENSIONS
Data corrected after a note from Georg Fischer by Peter Luschny, Sep 22 2025
STATUS
approved
