A090818 Nonprimes n such that 3*(3^n-1)*B(2n) is an integer, where B(k) denotes the k-th Bernoulli number.

1, 4, 12, 16, 25, 28, 32, 35, 36, 48, 49, 52, 55, 64, 65, 76, 77, 80, 84, 85, 91, 92, 95, 96, 108, 112, 115, 119, 121, 124, 125, 133, 143, 144, 145, 148, 155, 156, 160, 161, 164, 169, 172, 175, 185, 187, 188, 192, 196, 203, 205, 208, 209, 212, 215, 217, 221, 228