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 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 7 |
| 6 | 112 |
| 7 | 1092 |
| 8 | 8400 |
| 9 | 56100 |
| 10 | 341088 |
| 11 | 1939938 |
| 12 | 10498488 |
| 13 | 54679625 |
| 14 | 276276000 |
| 15 | 1362040680 |
| 16 | 6580248480 |
| 17 | 31256180280 |
| 18 | 146350008000 |
| 19 | 676868787000 |
| 20 | 3097351569312 |
| 21 | 14042319855102 |
| 22 | 63144549413792 |
| 23 | 281895309883000 |