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A057937 Number of prime factors of 7^n + 1 (counted with multiplicity). 1
3, 3, 4, 2, 5, 5, 5, 3, 5, 6, 5, 5, 5, 4, 7, 3, 4, 6, 5, 4, 8, 6, 4, 4, 6, 5, 6, 6, 4, 10, 6, 4, 8, 6, 11, 8, 5, 4, 9, 6, 7, 7, 10, 5, 12, 7, 4, 6, 12, 11, 8, 5, 7, 9, 13, 8, 9, 7, 7, 9, 4, 6, 14, 4, 9, 12, 6, 5, 8, 10, 5, 9, 6, 4, 11, 7, 12, 10, 7, 6, 10, 6, 5, 12, 8, 6, 8, 5, 8, 14, 11, 6, 9, 6, 11 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..372

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

FORMULA

a(n) = A057954(2n) - A057954(n). - T. D. Noe, Jun 19 2003

a(n) = A001222(A034491(n)). - Amiram Eldar, Feb 02 2020

MATHEMATICA

PrimeOmega[Table[7^n + 1, {n, 1, 30}]] (* Amiram Eldar, Feb 02 2020 *)

PROG

(MAGMA) f:=func<n|&+[p[2]: p in Factorization(n)]>; [f(7^n + 1):n in [1..110]]; // Marius A. Burtea, Feb 02 2020

CROSSREFS

Cf. A057934-A057941, A054992.

Cf. A001222, A034491, A057954.

Sequence in context: A062366 A278635 A294656 * A080216 A082924 A159636

Adjacent sequences:  A057934 A057935 A057936 * A057938 A057939 A057940

KEYWORD

nonn

AUTHOR

Patrick De Geest, Oct 15 2000

STATUS

approved

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Last modified June 6 01:16 EDT 2020. Contains 334858 sequences. (Running on oeis4.)