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

1,4

Links

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

Formula

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

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

Mathematica

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

Crossrefs

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

Sequence in context: A066921 A076649 A157235 * A077807 A280152 A281574

Adjacent sequences: A086286 A086287 A086288 * A086290 A086291 A086292

Keyword

nonn

Author

Reinhard Zumkeller, Jul 15 2003

Status

approved