Numbers n such that 2n+1 and 2n+3 are prime.
1, 2, 5, 8, 14, 20, 29, 35, 50, 53, 68, 74, 89, 95, 98, 113, 119, 134, 140, 155, 173, 209, 215, 230, 260, 284, 299, 308, 320, 329, 404, 410, 413, 428, 440, 509, 515, 524, 530, 545, 575, 614, 638, 644, 650, 659, 713, 725, 740, 743, 803, 809, 833, 848, 860
1
It is conjectured that this sequence is infinite.
T. D. Noe, Plot of 1000 terms
T. D. Noe, Table of 1000 terms
(Mma) Select[Range[1000], And @@ PrimeQ /@ ({1, 3} + 2*#) &]
nonn
T. D. Noe, Nov 05 2014