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 | 5 |
| 4 | 9 |
| 5 | 63 |
| 6 | 509 |
| 7 | 2959 |
| 8 | 22453 |
| 9 | 247949 |
| 10 | 3080991 |
| 11 | 28988331 |
| 12 | 407320739 |
| 13 | 5122243495 |
| 14 | 82583577967 |
| 15 | 1430027615585 |
| 16 | 22556817627789 |
| 17 | 395098668828675 |
| 18 | 7979894546677853 |
| 19 | 154786744386253387 |
| 20 | 3355612019167352821 |
| 21 | 78865333300205585345 |
| 22 | 1769663675666499515751 |