a(n) is the smallest k > 1 such that 2^n - 2 divides k^n - 1, for n > 1.

Terms

a(0) =3a(1) =7a(2) =13a(3) =31a(4) =5a(5) =127a(6) =253a(7) =511a(8) =293a(9) =2047a(10) =1013a(11) =8191a(12) =375a(13) =1885a(14) =6945a(15) =131071a(16) =21905a(17) =524287a(18) =1048573a(19) =202951a(20) =1095249a(21) =8388607a(22) =2180425a(23) =2784601a(24) =1080599a(25) =6046435a(26) =23113817a(27) =536870911a(28) =23884363a(29) =2147483647