|
|
A068078
|
|
Numbers n such that (sigma(n)+sigma(n+1))/n is an integer.
|
|
4
|
|
|
1, 10, 34, 136, 169, 2402, 5329, 21004, 38184, 41164, 54722, 458010, 776112, 1060802, 5026562, 10800112, 11108164, 14366402, 65676408, 87026656, 102944992, 387999360, 1488668112, 4414086384, 10499710072, 28645019964
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
COMMENTS
|
The quotient (sigma(a(n)))+sigma(a(n)+1))/a(n) is equal to 3 or 4 for n <= 33 and equal to 5 for a(34) = 1170035543040. - Giovanni Resta, Apr 04 2014
|
|
LINKS
|
|
|
MATHEMATICA
|
For[n=1, True, n++, If[Mod[DivisorSigma[1, n]+DivisorSigma[1, n+1], n]==0, Print[n]]]
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|