Positive integers of the form x^4 - y^4 that have exactly 4 divisors.

Terms

a(0) =15a(1) =65a(2) =671a(3) =3439a(4) =12209a(5) =102719a(6) =113521a(7) =178991a(8) =246559a(9) =515201a(10) =1124111a(11) =1342879a(12) =2964961a(13) =3940399a(14) =9951391a(15) =21254449a(16) =27220159a(17) =34209169a(18) =45259649a(19) =48986321a(20) =70710641a(21) =92110289a(22) =93084991a(23) =125620111a(24) =131687681a(25) =144402721a(26) =201792079a(27) =211782751a(28) =276694241