A218404 Numbers k for which sigma(k)/k - 1/4 is an integer.

40, 224, 360, 2016, 174592, 524160, 1571328, 492101632, 4428914688, 83350779494400, 2163091537152000, 2251247910912000, 2931032952207360, 7487050986455040, 155086041146982400, 369127262068899840, 12682035945406464000, 12848564519239680000

Offset: 1

Author

Zdenek Cervenka, Oct 28 2012

Keywords

• nonn
• more

Comments

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

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

Note that there are no terms here with abundancy 5/4. - Michel Marcus, Jun 26 2013

Crossrefs

Cf. A159907, A218405.

Extensions

a(8)-a(9) from Donovan Johnson, Oct 31 2012

a(10)-a(18) from Michel Marcus, Jun 26 2013