A125767 Least prime of the form n*T_i +/-1, where T is a triangular number.

2, 3, 2, 3, 29, 5, 41, 7, 53, 11, 67, 11, 79, 13, 89, 17, 101, 17, 113, 19, 127, 23, 137, 23, 149, 79, 163, 29, 173, 29, 311, 31, 197, 101, 211, 37, 223, 37, 233, 41, 409, 41, 257, 43, 269, 47, 281, 47, 293, 149, 307, 53, 317, 53, 331, 167, 569, 59, 353, 59, 367, 61, 379

Offset: 1

Author

Jonathan Vos Post & Robert G. Wilson v, Dec 01 2006

Keywords

• nonn

Crossrefs

Cf. A000217, A125765, A125766, A125768, A125769.

Programs

Mathematica

f[n_] := Block[{k = 1, s = {}, trnglr}, While[s == {}, trnglr = n*k(k + 1)/2; If[PrimeQ[trnglr - 1], AppendTo[s, trnglr - 1]]; If[PrimeQ[trnglr + 1], AppendTo[s, trnglr + 1]]; k++ ]; s[[1]]]; Array[f, 63]