A344870 - OEIS

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A344870

Number of distinct prime factors of n^n-1.

8

1, 2, 3, 3, 4, 4, 6, 6, 5, 4, 8, 5, 5, 7, 7, 4, 8, 3, 11, 9, 8, 6, 12, 11, 8, 9, 11, 9, 14, 4, 12, 8, 13, 10, 18, 9, 8, 10, 15, 7, 16, 6, 14, 17, 8, 5, 18, 17, 13, 14, 17, 7, 15, 10, 18, 8, 10, 5, 26, 7, 9, 14, 19, 14, 17, 9, 15, 11, 19, 7, 29, 12, 7, 11, 19, 12, 21, 8, 22, 25, 6, 6, 26, 16, 9, 15, 21, 8, 26, 11, 15, 13, 11, 11, 25, 8, 12, 14, 26

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OFFSET

2,2

LINKS

Amiram Eldar, Table of n, a(n) for n = 2..138

factordb, Factors of n^n-1.

FORMULA

a(n) = A001221(A048861(n)).

MATHEMATICA

a[n_] := PrimeNu[n^n - 1]; Array[a, 45, 2] (* Amiram Eldar, Jun 01 2021 *)

PROG

(PARI) a(n) = omega(n^n-1);

(Magma) [#PrimeDivisors(n^n-1): n in [2..100]];

CROSSREFS

Cf. A001221, A048861, A309941, A334167, A344869.

Sequence in context: A322007 A226107 A365659 * A318283 A105677 A230476

Adjacent sequences: A344867 A344868 A344869 * A344871 A344872 A344873

KEYWORD

nonn

AUTHOR

Seiichi Manyama, May 31 2021

STATUS

approved