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 | 12 |
| 2 | 100 |
| 3 | 720 |
| 4 | 4809 |
| 5 | 30744 |
| 6 | 191184 |
| 7 | 1167120 |
| 8 | 7033785 |
| 9 | 41999364 |
| 10 | 249075684 |
| 11 | 1469561184 |
| 12 | 8636441905 |
| 13 | 50600529840 |
| 14 | 295755641152 |
| 15 | 1725379046496 |
| 16 | 10050215851665 |
| 17 | 58470232877820 |
| 18 | 339832224226180 |
| 19 | 1973538115293360 |
| 20 | 11453616812552761 |
| 21 | 66436765880135112 |