A106799 - OEIS

A106799

Number of prime factors of n apart from 2 or 3, counted with multiplicity.

0, 0, 0, 0, 1, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1, 0, 1, 1, 1, 1, 1, 0, 2, 1, 0, 1, 1, 1, 1, 0, 1, 1, 2, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 2, 2, 1, 1, 1, 0, 2, 1, 1, 1, 1, 1, 1, 1, 1, 0, 2, 1, 1, 1, 1, 2, 1, 0, 1, 1, 2, 1, 2, 1, 1, 1, 0, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 0, 1, 2, 1, 2, 1, 1, 1, 1, 2

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OFFSET

1,25

COMMENTS

Self-similar in every second and in every third term, i.e., a(n) = a(2n) = a(3n).

Logarithmic since a(b*c) = a(b) + a(c).

Coincidentally, a(n) = A101040(n+78) for 1 < n < 20.

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

FORMULA

a(n) = A001222(n) - A007814(n) - A007949(n) = A087436(n) - A007949(n).

a(n) = A001222(A065330(n)). - Reinhard Zumkeller, May 19 2005