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 | 2 |
| 1 | 10 |
| 2 | 38 |
| 3 | 158 |
| 4 | 714 |
| 5 | 3378 |
| 6 | 16366 |
| 7 | 80326 |
| 8 | 397202 |
| 9 | 1972826 |
| 10 | 9824694 |
| 11 | 49005294 |
| 12 | 244672090 |
| 13 | 1222297474 |
| 14 | 6108298622 |
| 15 | 30531927062 |
| 16 | 152630937378 |
| 17 | 763068593322 |
| 18 | 3815084686150 |
| 19 | 19074648589630 |
| 20 | 95370918425066 |
| 21 | 476847618556370 |