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A057956 Number of prime factors of 5^n - 1 (counted with multiplicity). 3
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..448

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

Cf. A057951-A057958, A046051.

Cf. A001222, A024049, A085030.

Sequence in context: A239466 A129509 A015049 * A151734 A175027 A269837

Adjacent sequences:  A057953 A057954 A057955 * A057957 A057958 A057959

KEYWORD

nonn

AUTHOR

Patrick De Geest, Nov 15 2000

STATUS

approved

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Last modified September 19 15:09 EDT 2020. Contains 337178 sequences. (Running on oeis4.)