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 | 0 |
| 1 | 1 |
| 2 | 5 |
| 3 | 29 |
| 4 | 204 |
| 5 | 1714 |
| 6 | 16862 |
| 7 | 190826 |
| 8 | 2447512 |
| 9 | 35136696 |
| 10 | 558727872 |
| 11 | 9754239648 |
| 12 | 185546362416 |
| 13 | 3820734689472 |
| 14 | 84687887312688 |
| 15 | 2010622152615504 |
| 16 | 50908186083448320 |
| 17 | 1369376758488222336 |
| 18 | 38998680958184088960 |
| 19 | 1172297572938013827456 |
| 20 | 37092793335394301708544 |