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A186963 Number of prime factors in the expansion of the infinitary perfect number A007357(n) over distinct terms of A050376 0
2, 2, 2, 3, 4, 3, 4, 5, 4, 4, 6, 5, 6, 7, 6, 7, 6 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The total number of factors in the decomposition of A007357(n) in terms of A050376 is A187043(n). The subset of factors which are ordinary primes are counted here.

LINKS

Table of n, a(n) for n=1..17.

FORMULA

a(n) = A162642(A007357(n)). - R. J. Mathar, Mar 30 2011

EXAMPLE

The unique expansion of A007357(2)= 60 as a product of terms of A050376 is 3*4*5. Two of these factors, namely 3 and 5, are primes (A000040), so a(2)=2.

CROSSREFS

Cf. A007357, A050376, A187043

Sequence in context: A342247 A016729 A155940 * A060473 A055034 A112184

Adjacent sequences:  A186960 A186961 A186962 * A186964 A186965 A186966

KEYWORD

nonn

AUTHOR

Vladimir Shevelev, Mar 02 2011

STATUS

approved

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Last modified August 19 06:22 EDT 2022. Contains 356216 sequences. (Running on oeis4.)