OFFSET
1,1
LINKS
Donovan Johnson, Table of n, a(n) for n = 1..1000
PROG
(PARI) isok(n) = eulerphi(3*n+1) == sigma(n); \\ Michel Marcus, Nov 21 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Feb 20 2002
STATUS
approved