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 | 6 |
| 2 | 30 |
| 3 | 146 |
| 4 | 714 |
| 5 | 3534 |
| 6 | 17718 |
| 7 | 89898 |
| 8 | 461010 |
| 9 | 2386390 |
| 10 | 12455118 |
| 11 | 65478978 |
| 12 | 346448538 |
| 13 | 1843520670 |
| 14 | 9859734630 |
| 15 | 52974158938 |
| 16 | 285791932578 |
| 17 | 1547585781414 |
| 18 | 8408765223294 |
| 19 | 45830521556466 |
| 20 | 250501529133930 |
| 21 | 1372777379874926 |
| 22 | 7541129471504790 |
| 23 | 41518462993275786 |