(n-1)^(p-n+1)+n where p is the smallest prime > n-1.

Terms

a(0) =1a(1) =3a(2) =5a(3) =13a(4) =9a(5) =31a(6) =13a(7) =2409a(8) =521a(9) =91a(10) =21a(11) =133a(12) =25a(13) =28575a(14) =2759a(15) =241a(16) =33a(17) =307a(18) =37a(19) =130341a(20) =8021a(21) =463a(22) =45a(23) =148035913a(24) =7962649a(25) =390651a(26) =17603a(27) =757a(28) =57a(29) =871