A088873 Number of different values of A000005(d) where d is a divisor of n.

1, 2, 2, 3, 2, 3, 2, 4, 3, 3, 2, 5, 2, 3, 3, 5, 2, 5, 2, 5, 3, 3, 2, 6, 3, 3, 4, 5, 2, 4, 2, 6, 3, 3, 3, 6, 2, 3, 3, 6, 2, 4, 2, 5, 5, 3, 2, 8, 3, 5, 3, 5, 2, 6, 3, 6, 3, 3, 2, 7, 2, 3, 5, 7, 3, 4, 2, 5, 3, 4, 2, 8, 2, 3, 5, 5, 3, 4, 2, 8, 5, 3, 2, 7, 3, 3, 3, 6, 2, 7, 3, 5, 3, 3, 3, 9, 2, 5, 5, 6, 2, 4, 2, 6

Offset: 1

Author

Naohiro Nomoto, Nov 30 2003

Keywords

• easy
• nonn

Links

• Antti Karttunen, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000005.

Differs from A085082 and A181796 for the first time at n=24, where a(24) = 6, while A085082(24) = A181796(24) = 7.

Programs

Mathematica

a[n_] := Length@ DeleteDuplicates[DivisorSigma[0, Divisors[n]]]; Array[a, 100] (* Amiram Eldar, Mar 27 2024 *)

PARI

a(n) = {vals = Set(); fordiv(n, d, vals = Set(concat(vals, numdiv(d)))); return (length(vals));} \\ Michel Marcus, Jul 14 2013