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A107481 Number of different prime factors of the smallest n-perfect number. 1
1, 2, 3, 4, 7, 11, 19, 38 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..8.

Achim Flammenkamp, The Multiply Perfect Numbers Page,

FORMULA

a(n) = A001221(A007539(n))

EXAMPLE

a(4)=4 because the smallest 4-perfect number factorization is 2^5*3^3*5*7, which has 4 different prime factors.

CROSSREFS

Cf. A107482

Sequence in context: A226161 A188624 A256994 * A058521 A116628 A140463

Adjacent sequences:  A107478 A107479 A107480 * A107482 A107483 A107484

KEYWORD

hard,more,nonn

AUTHOR

Jose Brox (tautocrona(AT)terra.es), May 27 2005

STATUS

approved

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Last modified July 22 21:10 EDT 2019. Contains 325226 sequences. (Running on oeis4.)