Least k > 1 such that all divisors of (k^n-1)/(k-1) are == 1 (mod n).

Terms

a(0) =2a(1) =2a(2) =2a(3) =4a(4) =2a(5) =6a(6) =2a(7) =16a(8) =8a(9) =10a(10) =2a(11) =1260a(12) =2a(13) =28a(14) =24a(15) =16a(16) =2a(17) =162a(18) =2a(19) =2080a(20) =6a(21) =22a(22) =2a(23) =207480a(24) =7a(25) =52a(26) =27a(27) =420a(28) =2a(29) =43890