a(n) is the least k such that 4^k mod k = n.

Terms

a(0) =3a(1) =14a(2) =137243a(3) =5a(4) =6821a(5) =10a(6) =57a(7) =124a(8) =35a(9) =18a(10) =2791496231a(11) =244a(12) =51a(13) =505a(14) =199534799a(15) =20a(16) =30271293169a(17) =49a(18) =45a(19) =236a(20) =399531841a(21) =42a(22) =533a(23) =25a(24) =39a(25) =50a(26) =352957a(27) =36a(28) =995a(29) =98