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

1,1

Comments

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

Links

Table of n, a(n) for n=1..48.

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

Cf. A100486.

Sequence in context: A068059 A108868 A274261 * A238483 A238487 A138461

Adjacent sequences: A156910 A156911 A156912 * A156914 A156915 A156916

Keyword

nonn

Author

Zak Seidov, Feb 18 2009

Status

approved