Numbers of the form p*q, p and q prime with q=2*p-1.

Terms

a(0) =6a(1) =15a(2) =91a(3) =703a(4) =1891a(5) =2701a(6) =12403a(7) =18721a(8) =38503a(9) =49141a(10) =79003a(11) =88831a(12) =104653a(13) =146611a(14) =188191a(15) =218791a(16) =226801a(17) =269011a(18) =286903a(19) =385003a(20) =497503a(21) =597871a(22) =665281a(23) =721801a(24) =736291a(25) =765703a(26) =873181a(27) =954271a(28) =1056331a(29) =1314631