A032487 Numbers n such that 221*2^n+1 is prime.

1, 7, 9, 13, 21, 67, 77, 81, 89, 101, 117, 131, 161, 181, 229, 641, 753, 789, 911, 1351, 1461, 1819, 2391, 2951, 4381, 4531, 5633, 6577, 6671, 8521, 10059, 10453, 13571, 15427, 15541, 15969, 16601, 49013, 69831, 118213