A366651 Number of distinct prime divisors of 8^n - 1.

1, 2, 2, 4, 3, 4, 3, 6, 3, 6, 4, 8, 4, 6, 6, 9, 5, 6, 4, 11, 6, 8, 4, 12, 7, 7, 6, 12, 6, 11, 3, 12, 8, 10, 10, 12, 6, 8, 9, 15, 5, 11, 5, 14, 10, 8, 6, 17, 5, 13, 8, 16, 8, 12, 10, 17, 7, 10, 6, 21, 5, 7, 9, 15, 8, 15, 6, 19, 9, 20, 7, 18, 7, 12, 14, 16, 9

Offset: 1

Author

Sean A. Irvine, Oct 15 2023

Keywords

• nonn

Links

• Max Alekseyev, Table of n, a(n) for n = 1..500

Crossrefs

Cf. A024088, A001221, A057953, A366652, A366653, A366654.

Cf. A046800, A133801, A366604, A366611, A366620, A366632, A366660, A102347, A366681, A366707.

Programs

PARI

for(n = 1, 100, print1(omega(8^n - 1), ", "))

Formula

a(n) = omega(8^n-1) = A001221(A024088(n)).

a(n) = A046800(3*n). - Max Alekseyev, Jan 09 2024