A123524 Smallest odd number k such that sigma(x)=k has at least n solutions.

1, 31, 347529, 10773399, 4104665019, 28732655133, 28732655133, 35492068813383, 108695634368139, 461396894573979, 2529134502772059, 2529134502772059, 99414440839732473, 175792216832685999, 175792216832685999

Offset

1,2

Comments

Note that sigma(x) is odd iff x is in A028982 (numbers of the form m^2 or 2m^2 for m>0).

a(16) > 10^18. - Donovan Johnson, Jun 09 2011

Links

Table of n, a(n) for n=1..15.

Example

For n=3, sigma(x)=347529 has solutions x = 164836, 203522, 239121.

Crossrefs

Different from A123523.

Sequence in context: A107122 A059113 A057839 * A123523 A079595 A051155

Adjacent sequences: A123521 A123522 A123523 * A123525 A123526 A123527

Keyword

more,nonn

Author

T. D. Noe, Oct 02 2006

Extensions

35492068813383 from Martin Fuller, Oct 07 2006

a(9)-a(12) from Donovan Johnson, Dec 09 2008

a(13)-a(15) from Donovan Johnson, Jun 09 2011

Status

approved