OFFSET
1,1
LINKS
K. D. Bajpai, Table of n, a(n) for n = 1..3500
EXAMPLE
a(6)= 19: phi(sigma(12)) + sigma(phi(12))= 12+7= 19 which is prime.
a(9)= 47: phi(sigma(19)) + sigma(phi(19))= 8+39= 47 which is prime.
MAPLE
with(numtheory): KD:= proc() local a; a:= phi(sigma(n))+sigma(phi(n)); if isprime(a) then return (a) : fi; end: seq(KD(), n=1..10000);
CROSSREFS
KEYWORD
nonn,less
AUTHOR
K. D. Bajpai, Nov 03 2013
STATUS
approved