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 | 1 |
| 2 | 4 |
| 3 | 29 |
| 4 | 263 |
| 5 | 2672 |
| 6 | 29088 |
| 7 | 331749 |
| 8 | 3912660 |
| 9 | 47329811 |
| 10 | 583983656 |
| 11 | 7321173872 |
| 12 | 92990672635 |
| 13 | 1194113490556 |
| 14 | 15476763809428 |
| 15 | 202197552311829 |
| 16 | 2659975668005367 |
| 17 | 35205831900984144 |
| 18 | 468468683002725372 |
| 19 | 6263539340729569047 |
| 20 | 84103985900174324256 |
| 21 | 1133671250214654009000 |