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 | 4 |
| 4 | 9 |
| 5 | 23 |
| 6 | 68 |
| 7 | 205 |
| 8 | 655 |
| 9 | 2147 |
| 10 | 7218 |
| 11 | 24686 |
| 12 | 85760 |
| 13 | 301458 |
| 14 | 1070820 |
| 15 | 3836693 |
| 16 | 13851191 |
| 17 | 50333389 |
| 18 | 183965474 |
| 19 | 675825400 |
| 20 | 2494114694 |