A057939 Number of prime factors of 5^n + 1 (counted with multiplicity).

2, 2, 4, 2, 3, 3, 4, 3, 6, 4, 5, 3, 4, 3, 7, 3, 4, 5, 5, 4, 10, 4, 4, 4, 5, 5, 10, 3, 4, 7, 5, 4, 9, 6, 7, 6, 5, 4, 8, 5, 6, 6, 6, 3, 10, 3, 5, 5, 7, 7, 10, 5, 5, 6, 7, 7, 9, 3, 6, 6, 6, 4, 16, 4, 8, 7, 3, 7, 9, 7, 5, 6, 5, 5, 13, 5, 9, 10, 6, 6, 14, 6, 5, 7, 9, 5, 9, 7, 5, 12, 8, 4, 10, 6, 9, 7, 7, 7, 12

Offset

1,1

Links

Max Alekseyev, Table of n, a(n) for n = 1..471 (first 451 terms from Amiram Eldar)

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

Formula

a(n) = A057956(2n) - A057956(n). - T. D. Noe, Jun 19 2003

a(n) = A001222(A034474(n)). - Amiram Eldar, Feb 01 2020

Mathematica

PrimeOmega[5^Range[100]+1] (* Harvey P. Dale, Nov 27 2013 *)

Crossrefs

bigomega(b^n+1): A057934 (b=10), A057935 (b=9), A057936 (b=8), A057937 (b=7), A057938 (b=6), this sequence (b=5), A057940 (b=4), A057941 (b=3), A054992 (b=2).

Cf. A001222, A034474, A057956, A074478.

Sequence in context: A238745 A092607 A221861 * A163371 A061338 A135714

Adjacent sequences: A057936 A057937 A057938 * A057940 A057941 A057942

Keyword

nonn

Author

Patrick De Geest, Oct 15 2000

Status

approved