OFFSET
0,2
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..616
FORMULA
EXAMPLE
a(3) = 12: {}, 1, 2, 3, 12, 1|2, 13, 1|3, 23, 2|3, 123, 1|2|3.
MAPLE
b:= proc(n) option remember;
add(1/(d!*(n/d)!^d), d=numtheory[divisors](n))
end:
a:= n-> 1 + n! * add(b(k)/(n-k)!, k=1..n):
seq(a(n), n=0..30);
MATHEMATICA
b[n_] := b[n] = DivisorSum[n, 1/(#!*(n/#)!^#)&]; a[n_] := 1 + n! * Sum[b[k]/(n-k)!, {k, 1, n}]; Table[a[n], {n, 0, 30}] (* Jean-François Alcover, Dec 18 2016, after Alois P. Heinz *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Sep 17 2015
STATUS
approved