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 | 2 |
| 3 | 9 |
| 4 | 76 |
| 5 | 825 |
| 6 | 10206 |
| 7 | 143521 |
| 8 | 2313200 |
| 9 | 42482313 |
| 10 | 875799550 |
| 11 | 19972186311 |
| 12 | 498430219464 |
| 13 | 13509979971241 |
| 14 | 395352049852046 |
| 15 | 12425644029361725 |
| 16 | 417456939168255616 |
| 17 | 14929305882415781265 |
| 18 | 566234625018001351230 |
| 19 | 22701936510037394021395 |
| 20 | 959341639105178919209000 |