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 | 2 |
| 2 | 6 |
| 3 | 24 |
| 4 | 94 |
| 5 | 372 |
| 6 | 1508 |
| 7 | 6192 |
| 8 | 25638 |
| 9 | 106908 |
| 10 | 448356 |
| 11 | 1889040 |
| 12 | 7989676 |
| 13 | 33902504 |
| 14 | 144259944 |
| 15 | 615330784 |
| 16 | 2630199942 |
| 17 | 11263613484 |
| 18 | 48315367076 |
| 19 | 207556060816 |
| 20 | 892819376964 |
| 21 | 3845161246424 |
| 22 | 16578320962104 |
| 23 | 71548426931616 |
| 24 | 309070048163676 |
| 25 | 1336223562436632 |