A068077 Numbers k such that sigma(k) + sigma(k+1) = 4k.

1, 38184, 458010, 776112, 65676408, 1488668112, 4414086384, 28645019964, 46696401675, 65466785748, 70619381496, 176151711072

Offset: 1

Author

Dean Hickerson, Feb 16 2002

Keywords

• more
• nonn

Comments

a(13) > 10^13. - Giovanni Resta, Jul 11 2013

Crossrefs

Cf. A000203 (sigma), A067806, A068078.

Programs

Mathematica

For[n=1, True, n++, If[DivisorSigma[1, n]+DivisorSigma[1, n+1]==4n, Print[n]]]

Extensions

a(6)-a(8) from Donovan Johnson, Jan 31 2009

a(9)-a(12) from Giovanni Resta, Jul 11 2013