A057937 Number of prime factors of 7^n + 1 (counted with multiplicity).

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

Offset

1,1

Links

Max Alekseyev, Table of n, a(n) for n = 1..387 (first 372 terms from Amiram Eldar)

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

bigomega(b^n+1): A057934 (b=10), A057935 (b=9), A057936 (b=8), this sequence (b=7), A057938 (b=6), A057939 (b=5), A057940 (b=4), A057941 (b=3), A054992 (b=2).

Cf. A001222, A034491, A057954, A227575.

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