Semiprimes in A056107.

Terms

a(0) =4a(1) =49a(2) =301a(3) =589a(4) =973a(5) =2353a(6) =2701a(7) =3073a(8) =4333a(9) =5293a(10) =5809a(11) =6349a(12) =6913a(13) =7501a(14) =8749a(15) =9409a(16) =10801a(17) =11533a(18) =13069a(19) =14701a(20) =15553a(21) =16429a(22) =23233a(23) =24301a(24) =25393a(25) =27649a(26) =30001