a(n) = nextprime(5^n) - 5^n.

Terms

a(0) =1a(1) =2a(2) =4a(3) =2a(4) =6a(5) =12a(6) =4a(7) =12a(8) =22a(9) =26a(10) =4a(11) =14a(12) =58a(13) =6a(14) =12a(15) =42a(16) =24a(17) =2a(18) =12a(19) =56a(20) =48a(21) =24a(22) =18a(23) =38a(24) =58a(25) =14a(26) =12a(27) =38a(28) =34a(29) =62