Numbers that are one less than a square and have exactly 4 divisors.

Terms

a(0) =8a(1) =15a(2) =35a(3) =143a(4) =323a(5) =899a(6) =1763a(7) =3599a(8) =5183a(9) =10403a(10) =11663a(11) =19043a(12) =22499a(13) =32399a(14) =36863a(15) =39203a(16) =51983a(17) =57599a(18) =72899a(19) =79523a(20) =97343a(21) =121103a(22) =176399a(23) =186623a(24) =213443a(25) =272483a(26) =324899a(27) =359999a(28) =381923a(29) =412163