OFFSET
1,2
COMMENTS
a(13) > 10^13. - Giovanni Resta, Jul 11 2013
MATHEMATICA
For[n=1, True, n++, If[DivisorSigma[1, n]+DivisorSigma[1, n+1]==4n, Print[n]]]
CROSSREFS
KEYWORD
more,nonn
AUTHOR
Dean Hickerson, Feb 16 2002
EXTENSIONS
a(6)-a(8) from Donovan Johnson, Jan 31 2009
a(9)-a(12) from Giovanni Resta, Jul 11 2013
STATUS
approved