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 | 0 |
| 1 | 1 |
| 2 | 8 |
| 3 | 45 |
| 4 | 224 |
| 5 | 1050 |
| 6 | 4752 |
| 7 | 21021 |
| 8 | 91520 |
| 9 | 393822 |
| 10 | 1679600 |
| 11 | 7113106 |
| 12 | 29953728 |
| 13 | 125550100 |
| 14 | 524190240 |
| 15 | 2181340125 |
| 16 | 9051563520 |
| 17 | 37467344310 |
| 18 | 154754938800 |
| 19 | 637982011590 |
| 20 | 2625648168000 |
| 21 | 10789623755820 |
| 22 | 44277560801760 |
| 23 | 181478535620850 |
| 24 | 742984788858624 |
| 25 | 3038716500907500 |