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 | 0 |
| 2 | 120 |
| 3 | 348 |
| 4 | 2166 |
| 5 | 9528 |
| 6 | 44760 |
| 7 | 198816 |
| 8 | 877800 |
| 9 | 3809856 |
| 10 | 16379232 |
| 11 | 69769920 |
| 12 | 295055136 |
| 13 | 1239952512 |
| 14 | 5183031744 |
| 15 | 21564442752 |
| 16 | 89355535680 |
| 17 | 368925874944 |
| 18 | 1518322209600 |
| 19 | 6230763310464 |
| 20 | 25503209969088 |
| 21 | 104143201935360 |