Positive integers k such that k^20 + 1 is semiprime (A001358).

Terms

a(0) =2a(1) =4a(2) =46a(3) =154a(4) =266a(5) =472a(6) =748a(7) =1434a(8) =1738a(9) =2058a(10) =2204a(11) =2222a(12) =2428a(13) =2478a(14) =2510a(15) =2866a(16) =3132a(17) =3288a(18) =3576a(19) =3688a(20) =3756a(21) =4142a(22) =4506a(23) =4940a(24) =5164a(25) =6252a(26) =6330a(27) =6786a(28) =7180a(29) =7300