A125049 a(1) = 1. If a(n) is prime, a(n+1) = 2*a(n); otherwise, a(n+1) = 2*a(n) + 1.

1, 3, 6, 13, 26, 53, 106, 213, 427, 855, 1711, 3423, 6847, 13695, 27391, 54783, 109567, 219134, 438269, 876539, 1753079, 3506159, 7012318, 14024637, 28049275, 56098551, 112197103, 224394207, 448788415, 897576831, 1795153663, 3590307326