A218407 Numbers k for which sigma(k)/k - 2/5 is an integer.

30, 140, 2480, 6200, 40640, 297600, 997920, 64995840, 167751680, 1502582400, 42949345280, 183196016640, 687193456640, 1447428787200, 63870637017600, 326676430080000, 20797363851264000, 24871926476966400, 42981218625945600, 404918548479244800

Offset: 1

Author

Zdenek Cervenka, Oct 28 2012

Keywords

• nonn

Comments

a(12) > 10^11. - Donovan Johnson, Oct 31 2012

a(14) > 10^12. - Giovanni Resta, Nov 04 2012

Note that there are no terms here with abundancy 7/5 (k=1). - Michel Marcus, Jun 26 2013

Crossrefs

Cf. A218406, A218408, A218427.

Extensions

a(8)-a(11) from Donovan Johnson, Oct 31 2012

a(12)-a(13) from Giovanni Resta, Nov 04 2012

More terms from Michel Marcus, Jun 26 2013