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 | 19 |
| 4 | 130 |
| 5 | 1120 |
| 6 | 11960 |
| 7 | 151595 |
| 8 | 2230550 |
| 9 | 37361755 |
| 10 | 701873371 |
| 11 | 14610774346 |
| 12 | 333746628499 |
| 13 | 8298025724194 |
| 14 | 223049950124065 |
| 15 | 6444634486214748 |
| 16 | 199165237980655863 |
| 17 | 6555102341516877027 |
| 18 | 228905611339161301812 |
| 19 | 8452656930719845696590 |
| 20 | 329075775511339959533232 |
| 21 | 13471099892869946627980017 |