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 | 10 |
| 3 | 66 |
| 4 | 504 |
| 5 | 4210 |
| 6 | 37378 |
| 7 | 346846 |
| 8 | 3328188 |
| 9 | 32786630 |
| 10 | 329903058 |
| 11 | 3377919260 |
| 12 | 35095839848 |
| 13 | 369192702554 |
| 14 | 3925446804750 |
| 15 | 42126805350798 |
| 16 | 455792943581400 |
| 17 | 4967158911871358 |
| 18 | 54480174340453578 |
| 19 | 600994488311709056 |
| 20 | 6664356253639465480 |