| # | n (number) | Detail |
|---|---|---|
| 1 | 3 | 22 - 1 = 3 (Prime) |
| 2 | 7 | 23 - 1 = 7 (Prime) |
| 3 | 15 | 24 - 1 = 15 (Composite) |
| 4 | 31 | 25 - 1 = 31 (Prime) |
| 5 | 63 | 26 - 1 = 63 (Composite) |
| 6 | 127 | 27 - 1 = 127 (Prime) |
| 7 | 255 | 28 - 1 = 255 (Composite) |
| 8 | 511 | 29 - 1 = 511 (Composite) |
| 9 | 1023 | 210 - 1 = 1023 (Composite) |
| 10 | 2047 | 211 - 1 = 2047 (Composite) |
| 11 | 4095 | 212 - 1 = 4095 (Composite) |
| 12 | 8191 | 213 - 1 = 8191 (Prime) |
| 13 | 16383 | 214 - 1 = 16383 (Composite) |
| 14 | 32767 | 215 - 1 = 32767 (Composite) |
| 15 | 65535 | 216 - 1 = 65535 (Composite) |
| 16 | 131071 | 217 - 1 = 131071 (Prime) |
| 17 | 262143 | 218 - 1 = 262143 (Composite) |
| 18 | 524287 | 219 - 1 = 524287 (Prime) |
Mersenne numbers
Mersenne numbers have the form 2p - 1. A value is a Mersenne prime only when the result is prime (which implies p is prime).