Unique-period primes in base 4, sorted.
5, 7, 13, 17, 41, 241, 257, 61681, 65537, 15790321, 4278255361, 4562284561, 18446744069414584321, 291280009243618888211558641, 78919881726271091143763623681, 84159375948762099254554456081, 84179842077657862011867889681
1
T. D. Noe, Plot of 17 terms
Chris K. Caldwell, Unique prime
(Mma) nn = 1000; t4 = Table[c = Cyclotomic[n, 4]; c/GCD[n, c], {n, 2, nn}]; p4 = Select[t4, PrimePowerQ]; p4 = Table[FactorInteger[i][[1, 1]], {i, p4}]; Take[Sort[p4], 17]
Cf. A040017 (base-10 unique-period primes), A161509 (base 2), A064080.
Cf. S000020.
nonn,base
T. D. Noe, May 14 2014