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 | 5 |
| 3 | 13 |
| 4 | 34 |
| 5 | 89 |
| 6 | 356 |
| 7 | 1737 |
| 8 | 9065 |
| 9 | 49610 |
| 10 | 325832 |
| 11 | 2795584 |
| 12 | 28098632 |
| 13 | 310726442 |
| 14 | 3877921669 |
| 15 | 58896208285 |
| 16 | 1083370353616 |
| 17 | 22901813128125 |
| 18 | 548749450880000 |
| 19 | 15471093192996501 |
| 20 | 522297110942557556 |
| 21 | 20691062026775504896 |