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 | 1 |
| 2 | 3 |
| 3 | 7 |
| 4 | 23 |
| 5 | 70 |
| 6 | 320 |
| 7 | 985 |
| 8 | 4690 |
| 9 | 19600 |
| 10 | 121920 |
| 11 | 549600 |
| 12 | 3775200 |
| 13 | 21964800 |
| 14 | 186700800 |
| 15 | 983954400 |
| 16 | 7898290400 |
| 17 | 53301248000 |
| 18 | 523712716800 |
| 19 | 3600440064000 |
| 20 | 37065077913600 |
| 21 | 315001589760000 |
| 22 | 3848127528960000 |
| 23 | 30288467049984000 |
| 24 | 357688760600371200 |
| 25 | 3481899302289408000 |