A057956 Number of prime factors of 5^n - 1 (counted with multiplicity).

2, 4, 3, 6, 4, 7, 3, 8, 5, 7, 3, 10, 3, 7, 7, 11, 4, 11, 5, 11, 6, 8, 4, 13, 8, 7, 9, 10, 5, 14, 4, 14, 6, 8, 9, 16, 5, 10, 6, 15, 4, 16, 4, 12, 12, 8, 3, 17, 4, 13, 8, 12, 5, 19, 10, 13, 7, 9, 4, 21, 5, 9, 11, 18, 8, 15, 7, 14, 9, 16, 4, 22, 5, 10, 16, 14, 7, 14, 5, 20, 11, 10, 5, 22, 9, 10

Offset

1,1

Links

Max Alekseyev, Table of n, a(n) for n = 1..502 (first 448 terms from Amiram Eldar)

S. S. Wagstaff, Jr., The Cunningham Project

Formula

Mobius transform of A085030. - T. D. Noe, Jun 19 2003

a(n) = A001222(A024049(n)). - Amiram Eldar, Feb 01 2020

Mathematica

PrimeOmega[5^Range[90]-1] (* Harvey P. Dale, Dec 16 2017 *)

Crossrefs

bigomega(b^n-1): A057951 (b=10), A057952 (b=9), A057953 (b=8), A057954 (b=7), A057955 (b=6), this sequence (b=5), A057957 (b=4), A057958 (b=3), A046051 (b=2).

Cf. A001222, A024049, A074479, A085030.

Sequence in context: A129509 A341844 A015049 * A151734 A175027 A269837

Adjacent sequences: A057953 A057954 A057955 * A057957 A057958 A057959

Keyword

nonn

Author

Patrick De Geest, Nov 15 2000

Status

approved