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 | 0 |
| 2 | 1 |
| 3 | 6 |
| 4 | 44 |
| 5 | 430 |
| 6 | 5322 |
| 7 | 79184 |
| 8 | 1381144 |
| 9 | 27730602 |
| 10 | 630422390 |
| 11 | 16006336852 |
| 12 | 448982630340 |
| 13 | 13792542282974 |
| 14 | 460632431511826 |
| 15 | 16620059192605080 |
| 16 | 644338908974954672 |
| 17 | 26713929408696716242 |
| 18 | 1179487563859389821166 |