A275030 a(1) = 2. a(n) is the smallest prime such that a(n) - a(n-1) is a triangular number.

2, 3, 13, 19, 29, 107, 113, 149, 227, 233, 239, 317, 353, 359, 479, 557, 563, 569, 647, 653, 659, 1187, 1193, 1229, 1307, 1373, 1409, 1487, 1493, 1499, 1619, 1697, 1733, 1811, 1847, 1913, 1949, 2027, 2063, 2069, 2447, 2657, 2663, 2699, 2777, 2843, 2879, 2957, 2963

Offset: 1

Author

Ivan N. Ianakiev, Nov 13 2016

Keywords

• easy
• nonn

Crossrefs

Cf. A278139.

Programs

Mathematica

triQ[n_]:=IntegerQ[Sqrt[8n+1]];
NestList[(x=NextPrime[#]; While[!triQ[x-#],x=NextPrime[x]];x)&,2,100]

PARI

lista(nn) = {print1(p = 2, ", "); for (n=2, nn, q = nextprime(p+1); while (! ispolygonal(q-p, 3), q = nextprime(q+1)); print1(q, ", "); p = q;);} \\ Michel Marcus, Nov 13 2016