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 | 17 |
| 3 | 73 |
| 4 | 257 |
| 5 | 801 |
| 6 | 2305 |
| 7 | 6273 |
| 8 | 16385 |
| 9 | 41473 |
| 10 | 102401 |
| 11 | 247809 |
| 12 | 589825 |
| 13 | 1384449 |
| 14 | 3211265 |
| 15 | 7372801 |
| 16 | 16777217 |
| 17 | 37879809 |
| 18 | 84934657 |
| 19 | 189267969 |
| 20 | 419430401 |
| 21 | 924844033 |
| 22 | 2030043137 |
| 23 | 4437573633 |
| 24 | 9663676417 |
| 25 | 20971520001 |
| 26 | 45365592065 |
| 27 | 97844723713 |
| 28 | 210453397505 |
| 29 | 451508436993 |