A134740 Number of distinct prime factors in the n-th multiply perfect number A007691(n).

0, 2, 2, 3, 2, 3, 2, 4, 5, 4, 6, 5, 2, 5, 6, 6, 7, 5, 2, 7, 7, 6, 6, 6, 2, 7, 7, 7, 6, 8, 8, 8, 8, 6, 7, 8, 8, 9, 7, 8, 2, 9, 9, 9, 11, 10, 9, 10, 10, 8, 9, 11, 10, 10, 8, 11, 11, 10, 10, 11, 11, 9, 11, 9, 12, 11, 13, 13, 12, 11, 12, 12, 11, 13, 12, 12, 12, 11, 12, 13, 12, 11, 10, 13, 12, 11, 10

Offset

1,2

Comments

If a multiply perfect number k has abundancy m = sigma(k)/k, then k must have at least A005579(m) distinct prime factors.

Links

T. D. Noe, Table of n, a(n) for n=1..5000 (using Flammenkamp's data)

Achim Flammenkamp, The Multiply Perfect Numbers Page

Crossrefs

Cf. A007691.

Sequence in context: A374201 A336311 A339874 * A054714 A369032 A235922

Adjacent sequences: A134737 A134738 A134739 * A134741 A134742 A134743

Keyword

nonn

Author

T. D. Noe, Nov 07 2007

Status

approved