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 | 1 |
| 4 | 6 |
| 5 | 70 |
| 6 | 1215 |
| 7 | 27951 |
| 8 | 799708 |
| 9 | 27337500 |
| 10 | 1086190605 |
| 11 | 49162945645 |
| 12 | 2496308717826 |
| 13 | 140489907594114 |
| 14 | 8678436279296875 |
| 15 | 583701359488329915 |
| 16 | 42457773984656284920 |
| 17 | 3320786296452525792376 |
| 18 | 277898747312921495246937 |
| 19 | 24775177557380767822265625 |