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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
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
Sequence in context: A341823 A339548 A256994 * A058521 A116628 A140463
KEYWORD
nonn,hard,more
AUTHOR
Jose Brox (tautocrona(AT)terra.es), May 27 2005
STATUS
approved

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Last modified March 29 08:01 EDT 2024. Contains 371265 sequences. (Running on oeis4.)