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 | 7 |
| 2 | 56 |
| 3 | 336 |
| 4 | 1680 |
| 5 | 7392 |
| 6 | 29568 |
| 7 | 109824 |
| 8 | 384384 |
| 9 | 1281280 |
| 10 | 4100096 |
| 11 | 12673024 |
| 12 | 38019072 |
| 13 | 111132672 |
| 14 | 317521920 |
| 15 | 889061376 |
| 16 | 2444918784 |
| 17 | 6615662592 |
| 18 | 17641766912 |
| 19 | 46425702400 |
| 20 | 120706826240 |
| 21 | 310388981760 |
| 22 | 790081044480 |