OFFSET
1,1
EXAMPLE
sigma(499997) + p(499997) = 7890481 = 53^4.
PROG
(PARI) isok(n) = ispower(sigma(n) + prime(n), 4); \\ Michel Marcus, Jan 11 2014
CROSSREFS
KEYWORD
nonn
AUTHOR
Giovanni Resta, Feb 13 2006
STATUS
approved