Semiprimes in A054556.

Terms

a(0) =4a(1) =15a(2) =34a(3) =249a(4) =391a(5) =565a(6) =771a(7) =886a(8) =1915a(9) =3814a(10) =5149a(11) =5739a(12) =6046a(13) =7354a(14) =9169a(15) =10765a(16) =11611a(17) =15814a(18) =16321a(19) =18429a(20) =20665a(21) =22426a(22) =24259a(23) =28141a(24) =29499a(25) =32311a(26) =36769a(27) =39106a(28) =43161a(29) =48291