Indices k such that A020509(k)=Phi[k](-10) is prime, where Phi is a cyclotomic polynomial.

Terms

a(0) =4a(1) =5a(2) =7a(3) =12a(4) =19a(5) =24a(6) =31a(7) =36a(8) =38a(9) =46a(10) =48a(11) =53a(12) =67a(13) =75a(14) =78a(15) =120a(16) =186a(17) =196a(18) =293a(19) =320a(20) =327a(21) =369a(22) =634a(23) =641a(24) =713a(25) =770a(26) =931a(27) =1067a(28) =1172a(29) =1194