A156913 Numbers n with property that A100486(n) is square.

2, 4, 6, 11, 14, 21, 37, 75, 81, 176, 194, 310, 324, 332, 345, 399, 447, 612, 1122, 1209, 1614, 1874, 1921, 2186, 2329, 2482, 2509, 2874, 2940, 2975, 3230, 3611, 4185, 4650, 4923, 5172, 5248, 5543, 5587, 5673, 5714, 5764, 6038, 6078, 6250, 6430, 6976, 7023

Offset: 1

Author

Zak Seidov, Feb 18 2009

Keywords

• nonn

Comments

For n<2*10^6 there are 411 such numbers.

Examples

			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.
		

Crossrefs

Cf. A100486.

Programs

PARI

isok(n) = issquare(primepi(n) + prime(n)); \\ Michel Marcus, Oct 15 2013

Formula

pi(n) + n-th prime = square.