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) |
|---|---|
| 1 | 20 |
| 2 | 70 |
| 3 | 272 |
| 4 | 550 |
| 5 | 945 |
| 6 | 1575 |
| 7 | 3465 |
| 8 | 15015 |
| 9 | 47025 |
| 10 | 81081 |
| 11 | 153153 |
| 12 | 692835 |
| 13 | 1851759 |
| 14 | 3633903 |
| 15 | 6084351 |
| 16 | 22309287 |
| 17 | 95009481 |
| 18 | 131339637 |
| 19 | 277272567 |
| 20 | 1321122231 |
| 21 | 1516844043 |
| 22 | 5391411025 |
| 23 | 28816162375 |
| 24 | 40342627325 |
| 25 | 181667110625 |
| 26 | 186096635725 |
| 27 | 213239601575 |