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 | 1 |
| 2 | 2 |
| 3 | 8 |
| 4 | 24 |
| 5 | 72 |
| 6 | 264 |
| 7 | 952 |
| 8 | 3352 |
| 9 | 11960 |
| 10 | 43656 |
| 11 | 160840 |
| 12 | 594568 |
| 13 | 2215480 |
| 14 | 8300056 |
| 15 | 31191480 |
| 16 | 117674504 |
| 17 | 445439944 |
| 18 | 1691011464 |
| 19 | 6437425720 |
| 20 | 24564925848 |
| 21 | 93937631544 |
| 22 | 359943235080 |
| 23 | 1381706541512 |
| 24 | 5312678458888 |
| 25 | 20458827990456 |
| 26 | 78898261863832 |
| 27 | 304666752525368 |