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A125030 a(n) = sum of exponents in the prime-factorization of n which are noncomposite. 1
0, 1, 1, 2, 1, 2, 1, 3, 2, 2, 1, 3, 1, 2, 2, 0, 1, 3, 1, 3, 2, 2, 1, 4, 2, 2, 3, 3, 1, 3, 1, 5, 2, 2, 2, 4, 1, 2, 2, 4, 1, 3, 1, 3, 3, 2, 1, 1, 2, 3, 2, 3, 1, 4, 2, 4, 2, 2, 1, 4, 1, 2, 3, 0, 2, 3, 1, 3, 2, 3, 1, 5, 1, 2, 3, 3, 2, 3, 1, 1, 0, 2, 1, 4, 2, 2, 2, 4, 1, 4, 2, 3, 2, 2, 2, 6, 1, 3, 3, 4, 1, 3, 1, 4, 3 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

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

EXAMPLE

a(720) = 3, since the prime-factorization of 720 is 2^4 *3^2 *5^1 and 2 of the exponents in this factorization are non-composites (the exponents 2 and 1, which when added is 3).

MATHEMATICA

f[n_] := Plus @@ Select[Last /@ FactorInteger[n], # == 1 || PrimeQ[ # ] &]; Table[f[n], {n, 110}] (*Chandler*)

CROSSREFS

Cf. A125029.

Sequence in context: A147810 A055181 A073811 * A116479 A122810 A179953

Adjacent sequences:  A125027 A125028 A125029 * A125031 A125032 A125033

KEYWORD

nonn

AUTHOR

Leroy Quet, Nov 16 2006

EXTENSIONS

Extended by Ray Chandler, Nov 19 2006

STATUS

approved

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Last modified May 20 09:05 EDT 2013. Contains 225458 sequences.