A049588 Primes p such that x^56 = 2 has a solution mod p.

2, 7, 23, 31, 47, 73, 79, 89, 103, 151, 167, 191, 199, 223, 233, 257, 263, 271, 311, 359, 367, 383, 431, 439, 479, 487, 503, 599, 601, 607, 631, 647, 719, 727, 751, 823, 839, 863, 881, 887, 919, 937, 983, 991, 1031, 1039, 1063, 1087, 1103, 1151, 1217, 1223