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 | 1 |
| 3 | 3 |
| 4 | 4 |
| 5 | 65 |
| 6 | 576 |
| 7 | 5887 |
| 8 | 92464 |
| 9 | 1680345 |
| 10 | 34041520 |
| 11 | 774906011 |
| 12 | 19537590744 |
| 13 | 540890740117 |
| 14 | 16321259150392 |
| 15 | 533305854910935 |
| 16 | 18764822871806176 |
| 17 | 707498057530634033 |
| 18 | 28460428902580264416 |
| 19 | 1216828054782241792435 |