A152145 a(n) = least k such that 3*k*2^n-1 or 3*k*2^n+1 (or both) is prime.

1, 1, 1, 1, 1, 1, 1, 1, 1, 4, 2, 1, 1, 3, 3, 3, 4, 2, 1, 9, 6, 3, 9, 15, 13, 11, 9, 5, 4, 2, 1, 5, 4, 2, 1, 2, 1, 2, 1, 4, 2, 1, 2, 1, 5, 18, 9, 9, 5, 18, 9, 7, 8, 4, 2, 1, 9, 17, 18, 9, 15