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 | 4 |
| 2 | 26 |
| 3 | 232 |
| 4 | 2620 |
| 5 | 35696 |
| 6 | 568504 |
| 7 | 10349536 |
| 8 | 211799312 |
| 9 | 4809701440 |
| 10 | 119952692896 |
| 11 | 3257843882624 |
| 12 | 95680443760576 |
| 13 | 3020676745975552 |
| 14 | 101990226254706560 |
| 15 | 3666624057550245376 |
| 16 | 139813029266338603264 |