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) |
|---|---|
| 3 | 1 |
| 4 | 0 |
| 5 | 10 |
| 6 | 40 |
| 7 | 315 |
| 8 | 2464 |
| 9 | 22260 |
| 10 | 222480 |
| 11 | 2447445 |
| 12 | 29369120 |
| 13 | 381798846 |
| 14 | 5345183480 |
| 15 | 80177752655 |
| 16 | 1282844041920 |
| 17 | 21808348713320 |
| 18 | 392550276838944 |
| 19 | 7458455259940905 |
| 20 | 149169105198816960 |
| 21 | 3132551209175157490 |
| 22 | 68916126601853463240 |