A096691 - OEIS

A096691

Numbers n such that 8n^2 + 6n + 3 is prime.

0, 1, 2, 5, 8, 10, 13, 17, 20, 22, 23, 25, 31, 32, 37, 38, 40, 41, 43, 46, 47, 55, 61, 70, 80, 82, 85, 88, 91, 100, 101, 106, 107, 110, 112, 116, 118, 125, 131, 148, 151, 152, 155, 160, 161, 163, 166, 172, 173, 176, 196, 200, 202, 211, 212, 223, 226, 227, 245, 247

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,3

LINKS

Table of n, a(n) for n=1..60.

FORMULA

a(n) = A096689(n)/2.

MATHEMATICA

f[n_]:=n^2+(n+1)^2+(n+2); lst={}; Do[p=f[n]; If[PrimeQ[p], AppendTo[lst, n/2]], {n, 0, 6!}]; lst (* Vladimir Joseph Stephan Orlovsky, Jul 04 2009 *)

Select[Range[0, 300], PrimeQ[8#^2+6#+3]&] (* Harvey P. Dale, Jun 11 2015 *)

PROG

(PARI) is(n)=isprime(8*n^2+6*n+3) \\ Charles R Greathouse IV, May 22 2017