A231988 Primes of the form triangular(p) + 1, where p is a prime.

7, 29, 67, 191, 277, 947, 1129, 2557, 5779, 8647, 13367, 14029, 16111, 22367, 24977, 31627, 36857, 47279, 64621, 87991, 93097, 96581, 98347, 109279, 126757, 163307, 239087, 282377, 329267, 342379, 352381, 372817, 411779, 448879, 468029, 471907, 491537, 519691, 531997

Offset: 1

Author

Alex Ratushnyak, Nov 16 2013

Keywords

• nonn

Comments

Triangular(p) = p*(p+1)/2.

Crossrefs

Cf. A000040, A000217, A231847.

Programs

Mathematica

t = Select[Prime[Range[300]], PrimeQ[# (# + 1)/2 + 1] &]; t*(t + 1)/2 + 1 (* T. D. Noe, Nov 19 2013 *)

Formula

a(n) = A000217(A231847(n))+1.