OFFSET
1,2
COMMENTS
The sum of divisors of a square is always odd, therefore these numbers have the property that x=n^2, y=sigma(x) and z=sigma(y) are all three odd.
This is the subsequence of odd terms of A008847.
LINKS
M. F. Hasler, Table of n, a(n) for n = 1..122
CROSSREFS
KEYWORD
nonn
AUTHOR
M. F. Hasler, Dec 28 2013
STATUS
approved