A068406 Numbers n such that n and 2n+1 have the same number of prime divisors.

2, 3, 4, 5, 8, 9, 10, 11, 13, 22, 23, 28, 29, 34, 38, 41, 45, 46, 53, 55, 57, 58, 72, 76, 77, 80, 81, 83, 85, 87, 88, 89, 91, 92, 93, 94, 100, 104, 106, 108, 112, 113, 117, 118, 121, 122, 123, 124, 125, 128, 129, 131, 133, 143, 145, 147, 148, 152, 159, 160, 161, 162