a(n) is the least number k such that k*n+1 is a prime dividing n^n-1.

Terms

a(0) =1a(1) =4a(2) =1a(3) =2a(4) =1a(5) =4a(6) =2a(7) =2a(8) =1a(9) =1436a(10) =1a(11) =4a(12) =501969a(13) =4a(14) =1a(15) =644a(16) =1a(18) =2a(19) =2a(20) =1a(21) =20a(22) =3a(23) =4a(24) =36a(25) =4a(26) =1a(27) =2a(28) =1a(30) =8a(31) =2