A334167 a(n) is the number of divisors of n^n-1.

2, 4, 8, 12, 16, 16, 96, 128, 48, 16, 256, 48, 32, 128, 128, 40, 512, 12, 2048, 768, 256, 64, 6144, 4096, 768, 512, 4096, 768, 24576, 16, 6144, 768, 8192, 1024, 262144, 1152, 256, 1024, 49152, 256, 65536, 64, 24576, 196608, 384, 32, 393216, 327680, 12288, 24576

Offset: 2

Author

Todor Szimeonov, Apr 17 2020

Keywords

• nonn

Comments

25 values of the first 40 are powers of 2.

Links

• Max Alekseyev, Table of n, a(n) for n = 2..138

Crossrefs

Cf. A000005, A048861, A006486, A116895, A344859.

Programs

Mathematica

a[n_] := DivisorSigma[0, n^n - 1]; a /@ Range[2, 45] (* Giovanni Resta, Apr 17 2020 *)

PARI

a(n) = numdiv(n^n-1); \\ Michel Marcus, Apr 17 2020

Formula

a(n) = A000005(A048861(n)).

Extensions

More terms from Giovanni Resta, Apr 17 2020