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 | 1 |
| 1 | 3 |
| 2 | 15 |
| 3 | 270 |
| 4 | 5505 |
| 5 | 124818 |
| 6 | 3028200 |
| 7 | 76896180 |
| 8 | 2018211930 |
| 9 | 54311811330 |
| 10 | 1490518569747 |
| 11 | 41556060361920 |
| 12 | 1173726329836125 |
| 13 | 33513124885393020 |
| 14 | 965755118941566180 |
| 15 | 28051840723006217040 |
| 16 | 820439774630057541690 |