A366636 Number of distinct prime divisors of 7^n + 1.

1, 1, 2, 2, 2, 3, 4, 3, 3, 3, 4, 3, 5, 3, 3, 5, 3, 2, 5, 3, 4, 6, 5, 2, 4, 4, 4, 4, 6, 2, 8, 4, 4, 6, 5, 9, 8, 3, 3, 7, 6, 5, 6, 8, 5, 10, 6, 2, 6, 10, 8, 6, 5, 5, 8, 10, 8, 7, 6, 5, 9, 2, 5, 12, 4, 7, 11, 4, 5, 6, 8, 3, 9, 4, 3, 9, 7, 10, 8, 5, 6, 8, 5, 3, 12

Offset

0,3

Links

Max Alekseyev, Table of n, a(n) for n = 0..387

Formula

a(n) = omega(7^n+1) = A001221(A034491(n)).

Mathematica

PrimeNu[7^Range[0, 84] + 1] (* Paul F. Marrero Romero, Nov 11 2023 *)

Prog

(PARI) for(n = 0, 100, print1(omega(7^n + 1), ", "))

Crossrefs

Cf. A034491, A001221, A057937, A227575, A366632, A366637, A366638, A366639.

Cf. A046799, A366580, A366605, A366615, A366627, A366655, A366664, A119704, A366686, A366712.

Sequence in context: A163107 A275840 A178065 * A366655 A057748 A057747

Adjacent sequences: A366633 A366634 A366635 * A366637 A366638 A366639

Keyword

nonn

Author

Sean A. Irvine, Oct 15 2023

Status

approved