A061275 Smaller of two consecutive primes whose sum is a square.

17, 47, 71, 283, 881, 1151, 1913, 2591, 3527, 4049, 6047, 7193, 7433, 15137, 20807, 21617, 24197, 26903, 28793, 34847, 46817, 53129, 56443, 69191, 74489, 83231, 84047, 98563, 103049, 103967, 109507, 110441, 112337, 136237, 149057, 151247

Offset: 1

Author

Amarnath Murthy, Apr 25 2001

Keywords

• nonn
• easy

Examples

			a(4) = 283, the next prime is 293 and 283 + 293 = 576 = 24^2.
		

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..1000 from Harry J. Smith)

Crossrefs

Subset of A091624.

Cf. A000040, A064397, A206279, A206280, A206281.

Programs

Mathematica

Transpose[Select[Partition[Prime[Range[20000]],2,1],IntegerQ[Sqrt[Plus@@# ]]&]][[1]] (* Harvey P. Dale, Aug 04 2009 *)

PARI

{ default(primelimit, 550655327); n=0; q=2; forprime (p=3, 550655327, if (issquare(p+q), write("b061275.txt", n++, " ", q)); q=p ) } \\ Harry J. Smith, Jul 20 2009

Formula

a(n) = A000040(A064397(n)). - Amiram Eldar, Jun 28 2024

Extensions

More terms from Larry Reeves (larryr(AT)acm.org) and Asher Auel, May 15 2001

Offset changed from 0 to 1 by Harry J. Smith, Jul 20 2009