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 | 0 |
| 1 | 1 |
| 2 | 2 |
| 3 | 8 |
| 4 | 24 |
| 5 | 84 |
| 6 | 280 |
| 7 | 960 |
| 8 | 3264 |
| 9 | 11152 |
| 10 | 38048 |
| 11 | 129920 |
| 12 | 443520 |
| 13 | 1514304 |
| 14 | 5170048 |
| 15 | 17651712 |
| 16 | 60266496 |
| 17 | 205762816 |
| 18 | 702517760 |
| 19 | 2398545920 |
| 20 | 8189147136 |
| 21 | 27959497728 |
| 22 | 95459694592 |
| 23 | 325919784960 |
| 24 | 1112759746560 |
| 25 | 3799199420416 |