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) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 24 |
| 5 | 119 |
| 6 | 708 |
| 7 | 4914 |
| 8 | 38976 |
| 9 | 347790 |
| 10 | 3448212 |
| 11 | 37606536 |
| 12 | 447426144 |
| 13 | 5766888120 |
| 14 | 80047243080 |
| 15 | 1190459039364 |
| 16 | 18884750846976 |
| 17 | 318300264871440 |
| 18 | 5680496863401840 |
| 19 | 107008122578788800 |
| 20 | 2121893387875882944 |
| 21 | 44179385761361239200 |
| 22 | 963649662245743556160 |