A086289 Total number of prime factors of 7-smooth numbers.

0, 1, 1, 2, 1, 2, 1, 3, 2, 2, 3, 2, 2, 4, 3, 3, 2, 4, 2, 3, 3, 3, 5, 2, 4, 4, 3, 3, 5, 2, 3, 4, 4, 4, 3, 6, 3, 5, 3, 5, 4, 4, 4, 6, 3, 4, 3, 5, 5, 5, 3, 4, 7, 4, 4, 6, 3, 4, 6, 5, 5, 3, 5, 4, 7, 4, 5, 4, 6, 6, 4, 6, 5, 3, 4, 5, 8, 5, 5, 7, 4, 5, 4, 7, 6, 6, 3, 4, 6, 4, 5, 8, 5, 6, 5, 5, 7, 4, 7, 5

Offset: 1

Author

Reinhard Zumkeller, Jul 15 2003

Keywords

• nonn

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A001222, A002473, A086288, A086290, A086291.

Programs

Mathematica

PrimeOmega[Select[Range[500], Max[Transpose[FactorInteger[#]][[1]]] <= 7 &]] (* Amiram Eldar, Jan 06 2020 after G. C. Greubel at A086288 *)

Formula

a(n) = A001222(A002473(n)).

A086290(n) <= A086291(n) <= a(n).