A089767 Squares which when concatenated with a 1 gives prime.

1, 4, 25, 49, 64, 81, 225, 400, 676, 784, 900, 1089, 1225, 1369, 1600, 1681, 2209, 2304, 3249, 3364, 4096, 5041, 6889, 7225, 7396, 8100, 8281, 8649, 9801, 10816, 11025, 11236, 12100, 12544, 12769, 13924, 15876, 16384, 17424, 19881, 21609, 21904

Offset: 1

Author

Amarnath Murthy, Nov 23 2003

Keywords

• base
• nonn

Comments

Squares n such that 10*n+1 is prime. - Robert Israel, Dec 09 2017

Examples

			41, 4001, 6761 etc. are primes.
		

Links

• Robert Israel, Table of n, a(n) for n = 1..10000

Crossrefs

Intersection of A000290 and A024912.

Programs

MATLAB

A = []; count = 0; i = 1; while count < 60; s = i*i; if isprime(10*s + 1) A = [A s]; count = count + 1; end; i = i + 1; end; A

Maple

select(t -> isprime(10*t+1), map(`^`,[$1..300],2)); # Robert Israel, Dec 09 2017

Mathematica

Select[Range[150]^2, PrimeQ[10 # + 1] &] (* Michael De Vlieger, Dec 09 2017 *)

Extensions

Corrected and extended by David Wasserman, Feb 25 2004