OFFSET
0,2
FORMULA
a(n) = A000712(n)*n!
MAPLE
a:= proc(n) option remember; `if`(n=0, 1, 2*(n-1)!*
add(a(j)/j!*numtheory[sigma](n-j), j=0..n-1))
end:
seq(a(n), n=0..20); # Alois P. Heinz, Dec 20 2021
MATHEMATICA
nn = 16; Table[Sum[PartitionsP[k] PartitionsP[n - k], {k, 0, n}], {n, 0, nn}] Table[n!, {n, 0, nn}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Geoffrey Critzer, Dec 20 2021
STATUS
approved