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 | 3 |
| 2 | 6 |
| 3 | 24 |
| 4 | 72 |
| 5 | 240 |
| 6 | 696 |
| 7 | 2184 |
| 8 | 6480 |
| 9 | 19656 |
| 10 | 58800 |
| 11 | 177144 |
| 12 | 530640 |
| 13 | 1594320 |
| 14 | 4780776 |
| 15 | 14348640 |
| 16 | 43040160 |
| 17 | 129140160 |
| 18 | 387400104 |
| 19 | 1162261464 |
| 20 | 3486725280 |
| 21 | 10460350992 |
| 22 | 31380882456 |
| 23 | 94143178824 |
| 24 | 282428998560 |
| 25 | 847288609200 |
| 26 | 2541864234000 |
| 27 | 7625597465304 |