OFFSET
1,2
COMMENTS
The smallest k>1 such that k divides sigma(k*n) is always 2, 3 or 6. Sequence generates squares but not all the squares (49, 169, 196, 361, 441, 676, 784, ... are the first squares not in the sequence).
This is not the sequence of solutions to sigma(n) == 1 (mod 6), because 2401 is in this sequence but sigma(2401) == 5 (mod 6). See A074384 for more examples. - R. J. Mathar, May 19 2020
FORMULA
{n: A049605(n) = 6}. - R. J. Mathar, May 19 2020
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Benoit Cloitre, Jul 26 2002
STATUS
approved