Indices of prime generalized tetranacci numbers, A073817.

Terms

a(0) =2a(1) =3a(2) =8a(3) =9a(4) =16a(5) =19a(6) =24a(7) =27a(8) =46a(9) =68a(10) =71a(11) =78a(12) =107a(13) =198a(14) =309a(15) =377a(16) =477a(17) =1057a(18) =1631a(19) =2419a(20) =3974a(21) =4293a(22) =8247a(23) =10513a(24) =10709a(25) =12011a(26) =15042a(27) =30543a(28) =31607a(29) =39664