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 | 10 |
| 2 | 75 |
| 3 | 450 |
| 4 | 2375 |
| 5 | 11302 |
| 6 | 49820 |
| 7 | 205900 |
| 8 | 807195 |
| 9 | 3023020 |
| 10 | 10883842 |
| 11 | 37840290 |
| 12 | 127544465 |
| 13 | 418051040 |
| 14 | 1336017805 |
| 15 | 4172140618 |
| 16 | 12755565695 |
| 17 | 38242019080 |
| 18 | 112591545060 |
| 19 | 325939921700 |
| 20 | 928795211589 |
| 21 | 2607843351420 |