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 | 6 |
| 3 | 38 |
| 4 | 240 |
| 5 | 1516 |
| 6 | 9576 |
| 7 | 60488 |
| 8 | 382080 |
| 9 | 2413456 |
| 10 | 15244896 |
| 11 | 96296288 |
| 12 | 608267520 |
| 13 | 3842197696 |
| 14 | 24269721216 |
| 15 | 153302722688 |
| 16 | 968355778560 |
| 17 | 6116740116736 |
| 18 | 38637152257536 |
| 19 | 244056393778688 |
| 20 | 1541612667187200 |