A050850 Numbers n such that 197*2^n-1 is prime.

2, 16, 20, 22, 40, 82, 112, 178, 230, 302, 304, 328, 374, 442, 472, 500, 580, 694, 1264, 1634, 1784, 3080, 5722, 7174, 8908, 18502, 18746, 39094, 99338, 170066, 202534, 325610, 510940, 569222, 635042, 825188