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 | 4 |
| 3 | 15 |
| 4 | 60 |
| 5 | 240 |
| 6 | 956 |
| 7 | 3809 |
| 8 | 15180 |
| 9 | 60495 |
| 10 | 241080 |
| 11 | 960736 |
| 12 | 3828664 |
| 13 | 15257745 |
| 14 | 60804180 |
| 15 | 242312895 |
| 16 | 965649716 |
| 17 | 3848244944 |
| 18 | 15335777460 |
| 19 | 61115150865 |
| 20 | 243552156060 |
| 21 | 970588338271 |
| 22 | 3867926023024 |
| 23 | 15414209227200 |
| 24 | 61427712082800 |
| 25 | 244797754857825 |