Numbers k such that k+1, 2*k+1 and k^2+1 are primes.

Terms

a(0) =1a(1) =2a(2) =6a(3) =36a(4) =156a(5) =210a(6) =270a(7) =306a(8) =576a(9) =690a(10) =936a(11) =966a(12) =2136a(13) =2310a(14) =2550a(15) =2706a(16) =2850a(17) =3390a(18) =3966a(19) =4026a(20) =4176a(21) =4260a(22) =4566a(23) =4590a(24) =5226a(25) =5430a(26) =5850a(27) =6120a(28) =6216a(29) =6360