Largest prime < n^4.

Terms

a(0) =13a(1) =79a(2) =251a(3) =619a(4) =1291a(5) =2399a(6) =4093a(7) =6553a(8) =9973a(9) =14639a(10) =20731a(11) =28559a(12) =38393a(13) =50599a(14) =65521a(15) =83497a(16) =104971a(17) =130307a(18) =159979a(19) =194479a(20) =234239a(21) =279823a(22) =331769a(23) =390581a(24) =456959a(25) =531383a(26) =614639a(27) =707279a(28) =809993a(29) =923513