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

1,2

Comments

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

Links

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

Example

41, 4001, 6761 etc. are primes.

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 *)

Prog

(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

Crossrefs

Intersection of A000290 and A024912.

Sequence in context: A335350 A199772 A245697 * A337173 A135784 A131069

Adjacent sequences: A089764 A089765 A089766 * A089768 A089769 A089770

Keyword

base,nonn

Author

Amarnath Murthy, Nov 23 2003

Extensions

Corrected and extended by David Wasserman, Feb 25 2004

Status

approved