A117314 Twin-prime pairs expressible as the sum of two triangular numbers.

11, 13, 29, 31, 137, 139, 191, 193, 461, 463, 659, 661, 821, 823, 1091, 1093, 1721, 1723, 2027, 2029, 2081, 2083, 2711, 2713, 3359, 3361, 3539, 3541, 3917, 3919, 6131, 6133, 6761, 6763, 7589, 7591, 7877, 7879, 7949, 7951, 8219, 8221, 9461, 9463, 9857

Offset: 1

Author

Greg Huber, Apr 24 2006

Keywords

• easy
• nonn

Examples

			a(1) = 11 = 1 + 10; a(2) = 13 = 3 + 10.
		

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A117048, A117112, A118638.

Programs

Mathematica

s = Select[Union@ Flatten@ Table[i(i + 1)/2 + j(j + 1)/2, {i, 200}, {j, 0, i}], PrimeQ@ # &]; t = Select[Range@Length@s - 1, s[[ # ]] + 2 == s[[ # + 1]] &]; Sort@Join[s[[t]], s[[t + 1]]] (* Robert G. Wilson v, Apr 27 2006 *)

Extensions

More terms from Robert G. Wilson v, Apr 27 2006