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 | 0 |
| 1 | 5 |
| 2 | 30 |
| 3 | 135 |
| 4 | 660 |
| 5 | 3145 |
| 6 | 15810 |
| 7 | 78155 |
| 8 | 391320 |
| 9 | 1953405 |
| 10 | 9768870 |
| 11 | 48828175 |
| 12 | 244157820 |
| 13 | 1220703185 |
| 14 | 6103593930 |
| 15 | 30517584915 |
| 16 | 152588282640 |
| 17 | 762939453205 |
| 18 | 3814699250430 |
| 19 | 19073486328215 |
| 20 | 95367441415140 |
| 21 | 476837158360185 |
| 22 | 2384185839844050 |
| 23 | 11920928955078235 |
| 24 | 59604645020345640 |