A366780 - OEIS

A366780

Number of distinct prime divisors of A000073(n) (tribonacci numbers).

0, 0, 1, 1, 1, 1, 2, 2, 1, 1, 2, 3, 2, 3, 2, 3, 1, 3, 4, 3, 3, 2, 2, 2, 3, 3, 3, 5, 3, 4, 5, 3, 4, 3, 5, 4, 5, 3, 5, 3, 2, 4, 2, 4, 5, 4, 4, 6, 2, 5, 5, 6, 3, 5, 7, 5, 2, 3, 5, 4, 6, 5, 4, 7, 3, 2, 4, 4, 3, 3, 4, 5, 2, 6, 6, 6, 5, 3, 6, 5, 4, 2, 6, 3, 6, 1, 7

(list; graph; refs; listen; history; text; internal format)

OFFSET

2,7

LINKS

Amiram Eldar, Table of n, a(n) for n = 2..365

FORMULA

a(n) = A001221(A000073(n)).

EXAMPLE

a(8)=2 because the 8th tribonacci number 24 = 2^3*3 has 2 distinct prime factors.

MATHEMATICA

PrimeNu[LinearRecurrence[{1, 1, 1}, {1, 1, 2}, 87]] (* Amiram Eldar, Oct 23 2023 *)

CROSSREFS