OFFSET
0,5
COMMENTS
If k in the sum in the definition is taken only over the proper divisors of n, the sequence is the same.
a(p) = a(p-1) if p is a prime. - Robert G. Wilson v, Aug 23 2004
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..1000
EXAMPLE
a(8) = a(1)*a(7) + a(2)*a(6) + a(4)*a(4) + a(8)*a(0) = 5 + 5 + 4 + 0 = 14.
MAPLE
a:= proc(n) option remember; `if`(n<2, n, add(
a(d)*a(n-d), d=numtheory[divisors](n) minus {n}))
end:
seq(a(n), n=0..40); # Alois P. Heinz, Jul 26 2015
MATHEMATICA
a[0] = 0; a[1] = 1; a[n_] := a[n] = Block[{d = Drop[ Divisors[n], -1]}, Plus @@ Flatten[(a /@ d)*(a /@ (n - d))]]; Table[ a[n], {n, 0, 38}] (* Robert G. Wilson v, Aug 23 2004 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Leroy Quet, Aug 22 2004
EXTENSIONS
More terms from Robert G. Wilson v, Aug 23 2004
STATUS
approved