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 | 1 |
| 1 | 0 |
| 2 | 0 |
| 3 | 56 |
| 4 | 126 |
| 5 | 2016 |
| 6 | 16632 |
| 7 | 181368 |
| 8 | 2091375 |
| 9 | 26442416 |
| 10 | 361224864 |
| 11 | 5305691664 |
| 12 | 83351722636 |
| 13 | 1394398680192 |
| 14 | 24744942004464 |
| 15 | 464237094657744 |
| 16 | 9179911341932877 |
| 17 | 190814604739422048 |
| 18 | 4159156093506930208 |