Indices k such that A020503(k)=Phi[k](-4) is prime, where Phi is a cyclotomic polynomial.

Terms

a(0) =3a(1) =4a(2) =8a(3) =12a(4) =16a(5) =20a(6) =28a(7) =40a(8) =60a(9) =92a(10) =96a(11) =104a(12) =140a(13) =148a(14) =156a(15) =300a(16) =356a(17) =408a(18) =596a(19) =612a(20) =692a(21) =732a(22) =756a(23) =800a(24) =952a(25) =996a(26) =1004a(27) =1228a(28) =1268a(29) =2240