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A057935 Number of prime factors of 9^n + 1 (counted with multiplicity). 2
2, 2, 3, 3, 4, 3, 4, 2, 4, 3, 4, 6, 4, 4, 6, 2, 4, 4, 4, 5, 7, 5, 4, 4, 8, 4, 5, 6, 4, 7, 5, 2, 6, 5, 9, 8, 5, 6, 7, 5, 5, 10, 7, 6, 9, 4, 4, 6, 9, 6, 8, 7, 6, 9, 8, 9, 9, 5, 3, 11, 6, 4, 11, 6, 8, 9, 9, 8, 6, 9, 5, 6, 6, 6, 13, 4, 8, 7, 5, 4, 7, 6, 5, 11, 8, 5, 8, 7, 4, 11, 7, 9, 9, 5, 9, 7, 5, 6, 10, 7, 6 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..329

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

FORMULA

a(n) = A057952(2n) - A057952(n). - T. D. Noe, Jun 19 2003

a(n) = A001222(A062396(n)) = A057941(2*n). - Amiram Eldar, Feb 02 2020

MATHEMATICA

PrimeOmega[Table[9^n + 1, {n, 1, 30}]] (* Amiram Eldar, Feb 02 2020 *)

PROG

(MAGMA) f:=func<n|&+[p[2]: p in Factorization(n)]>; [f(9^n + 1):n in [1..100]]; // Marius A. Burtea, Feb 02 2020

CROSSREFS

Cf. A002592, A046053, A057934-A057941, A054992.

Cf. A001222, A057941, A057952, A062396.

Sequence in context: A324863 A332894 A269989 * A292042 A282715 A124831

Adjacent sequences:  A057932 A057933 A057934 * A057936 A057937 A057938

KEYWORD

nonn

AUTHOR

Patrick De Geest, Oct 15 2000

STATUS

approved

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Last modified March 30 06:59 EDT 2020. Contains 333119 sequences. (Running on oeis4.)