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 | 3 |
| 3 | 13 |
| 4 | 64 |
| 5 | 416 |
| 6 | 2736 |
| 7 | 23472 |
| 8 | 207936 |
| 9 | 2113344 |
| 10 | 22584960 |
| 11 | 284722560 |
| 12 | 3576337920 |
| 13 | 52240412160 |
| 14 | 768727895040 |
| 15 | 12228344755200 |
| 16 | 206114911027200 |
| 17 | 3838718125670400 |
| 18 | 71231050830643200 |
| 19 | 1468632692485324800 |
| 20 | 30345814652977152000 |
| 21 | 666456931810639872000 |
| 22 | 15172961921551171584000 |