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 | 4 |
| 2 | 18 |
| 3 | 114 |
| 4 | 936 |
| 5 | 9480 |
| 6 | 114480 |
| 7 | 1607760 |
| 8 | 25764480 |
| 9 | 464123520 |
| 10 | 9286099200 |
| 11 | 204334099200 |
| 12 | 4904497382400 |
| 13 | 127523158963200 |
| 14 | 3570735629260800 |
| 15 | 107123376552192000 |
| 16 | 3427968972460032000 |
| 17 | 116551300751069184000 |