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A169611 Number of prime divisors of n that are not greater than 3, counted with multiplicity. 9
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

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

FORMULA

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

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

a(n) = A001222(A065331(n)). - Reinhard Zumkeller, Nov 19 2015

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) ; # R. J. Mathar, Dec 04 2009

MATHEMATICA

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

PROG

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

(Haskell)

a169611 = a001222 . a065331  -- Reinhard Zumkeller, Nov 19 2015

CROSSREFS

Cf. A001222, A106799.

Cf. A007814, A007949, A065331.

Sequence in context: A273846 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 December 9 20:00 EST 2016. Contains 278986 sequences.