This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 5 |
| 3 | 15 |
| 4 | 51 |
| 5 | 85 |
| 6 | 255 |
| 7 | 3855 |
| 8 | 13107 |
| 9 | 21845 |
| 10 | 65535 |
| 11 | 16711935 |
| 12 | 252645135 |
| 13 | 858993459 |
| 14 | 1431655765 |
| 15 | 4294967295 |
| 16 | 281470681808895 |
| 17 | 71777214294589695 |
| 18 | 1085102592571150095 |
| 19 | 3689348814741910323 |
| 20 | 6148914691236517205 |