A067806 Numbers n such that sigma(n+1)+sigma(n)=3n.

10, 34, 136, 169, 2402, 5329, 21004, 41164, 54722, 1060802, 5026562, 10800112, 11108164, 14366402, 87026656, 102944992, 10499710072, 107000850688, 220200311872, 924354816004

Offset

1,1

Comments

a(21) > 10^13. - Giovanni Resta, Jul 11 2013

Links

Table of n, a(n) for n=1..20.

Mathematica

For[n=1, True, n++, If[DivisorSigma[1, n]+DivisorSigma[1, n+1]==3n, Print[n]]]

Crossrefs

Cf. A068077, A068078.

Sequence in context: A166066 A232583 A068078 * A001446 A264671 A341300

Adjacent sequences: A067803 A067804 A067805 * A067807 A067808 A067809

Keyword

more,nonn

Author

Benoit Cloitre, Feb 07 2002

Extensions

Edited by Dean Hickerson, Feb 16 2002

a(17) from Donovan Johnson, Jan 31 2009

a(18)-a(20) from Giovanni Resta, Jul 11 2013

Status

approved