A107481 - OEIS

A107481

Number of different prime factors of the smallest n-perfect number.

1, 2, 3, 4, 7, 11, 19, 38

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

LINKS

FORMULA

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

KEYWORD

nonn,hard,more

AUTHOR

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

STATUS

approved