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 | 2 |
| 2 | 9 |
| 3 | 73 |
| 4 | 849 |
| 5 | 12651 |
| 6 | 228493 |
| 7 | 4836301 |
| 8 | 117204545 |
| 9 | 3196763983 |
| 10 | 96842596701 |
| 11 | 3224356269597 |
| 12 | 116981406934417 |
| 13 | 4591908332288837 |
| 14 | 193846634326107701 |
| 15 | 8755364023207809301 |
| 16 | 421214258699748184321 |
| 17 | 21500563181275847468503 |
| 18 | 1160430732790051008442141 |
| 19 | 66020998289431649938896445 |