OFFSET
1,1
COMMENTS
For n<2*10^6 there are 411 such numbers.
FORMULA
pi(n) + n-th prime = square.
EXAMPLE
n=2 pi(2)+p(2)=2+2=4, n=4 pi(4)+p(4)=2+7=9, n=6 pi(6)+p(6)=3+13=16, etc.
PROG
(PARI) isok(n) = issquare(primepi(n) + prime(n)); \\ Michel Marcus, Oct 15 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
Zak Seidov, Feb 18 2009
STATUS
approved