

A066244


Numbers n such that sigma(n+2)2sigma(n+1)+sigma(n) = n.


0




OFFSET

1,1


COMMENTS

The equation here is the difference equation (applied to sigma) corresponding to the differential equation y" = x (Hooke's law with constant = 1).
a(6) > 10^13.  Giovanni Resta, Jul 13 2015


LINKS

Table of n, a(n) for n=1..5.


EXAMPLE

sigma(40)2*sigma(39)+sigma(38) = 90  2*56 + 60 = 38, so 38 is a term of the sequence.


MATHEMATICA

Select[Range[1, 10^6], DivisorSigma[1, # + 2]  2*DivisorSigma[1, # + 1] + DivisorSigma[1, # ] == # &]


CROSSREFS

Sequence in context: A184994 A132396 A263374 * A055689 A028442 A062982
Adjacent sequences: A066241 A066242 A066243 * A066245 A066246 A066247


KEYWORD

more,nonn


AUTHOR

Joseph L. Pe, Dec 19 2001


EXTENSIONS

a(5) from Donovan Johnson, Feb 01 2009


STATUS

approved



