OFFSET
1,1
COMMENTS
Conjecture: sequence gives odd values only.
LINKS
Donovan Johnson, Table of n, a(n) for n = 1..1000
PROG
(PARI) isok(n) = sigma(n-3)+sigma(n+3) == sigma(2*n); \\ Michel Marcus, Nov 20 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Feb 18 2002
EXTENSIONS
More terms from Michel Marcus, Nov 20 2013
STATUS
approved