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 | 3 |
| 3 | 9 |
| 4 | 36 |
| 5 | 166 |
| 6 | 968 |
| 7 | 6372 |
| 8 | 49368 |
| 9 | 429240 |
| 10 | 4198176 |
| 11 | 45268416 |
| 12 | 535590144 |
| 13 | 6879038400 |
| 14 | 95412176640 |
| 15 | 1419918128640 |
| 16 | 22571960048640 |
| 17 | 381596438638080 |
| 18 | 6836248502784000 |
| 19 | 129352329079142400 |
| 20 | 2577689266340966400 |
| 21 | 53957785094515814400 |
| 22 | 1183674698660605132800 |