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A169611 Number of prime divisors of n which are not greater than 3, counted with multiplicity. 8
0, 1, 1, 2, 0, 2, 0, 3, 2, 1, 0, 3, 0, 1, 1, 4, 0, 3, 0, 2, 1, 1, 0, 4, 0, 1, 3, 2, 0, 2, 0, 5, 1, 1, 0, 4, 0, 1, 1, 3, 0, 2, 0, 2, 2, 1, 0, 5, 0, 1, 1, 2, 0, 4, 0, 3, 1, 1, 0, 3, 0, 1, 2, 6, 0, 2, 0, 2, 1, 1, 0, 5, 0, 1, 1, 2, 0, 2, 0, 4, 4, 1, 0, 3, 0, 1, 1, 3, 0, 3, 0, 2, 1, 1, 0, 6, 0, 1, 2, 2, 0, 2, 0, 3, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Table of n, a(n) for n=1..105.

FORMULA

a(n)=A001222(n)-A106799(n).

a(n)=A007814(n)+A007949(n). [From R. J. Mathar, Dec 04 2009]

MAPLE

A169611 := proc(n) local f; a := 0 ; for f in ifactors(n)[2] do if op(1, f) <= 3 then a := a+op(2, f) ; end if; end do: return a; end proc: seq(A169611(n), n=1..100) ; [From R. J. Mathar, Dec 04 2009]

MATHEMATICA

f[n_] := Plus @@ Last /@ Select[ FactorInteger@ n, 1 < #[[1]] < 4 &]; Array[f, 105] [From Robert G. Wilson v, Dec 19 2009]

PROG

(PARI) A169611(n)=valuation(n, 2)+valuation(n, 3)  \\ - M. F. Hasler, Aug 24 2012

CROSSREFS

Cf. A001222, A106799.

Sequence in context: A029188 A090290 A153585 * A242460 A144494 A136166

Adjacent sequences:  A169608 A169609 A169610 * A169612 A169613 A169614

KEYWORD

nonn

AUTHOR

Juri-Stepan Gerasimov, Dec 03 2009

EXTENSIONS

Definition corrected by M. F. Hasler, Aug 24 2012

STATUS

approved

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Last modified August 1 19:36 EDT 2014. Contains 245137 sequences.