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 | 28 |
| 3 | 1120 |
| 4 | 51520 |
| 5 | 2555392 |
| 6 | 132880384 |
| 7 | 7137574912 |
| 8 | 392566620160 |
| 9 | 21983730728960 |
| 10 | 1248675905404928 |
| 11 | 71742106565083136 |
| 12 | 4161042180774821888 |
| 13 | 243260927491451125760 |
| 14 | 14317643160925409116160 |
| 15 | 847604475126784219676672 |
| 16 | 50432466270043661070761984 |
| 17 | 3014081513550844685170245632 |