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 | 0 |
| 2 | 0 |
| 3 | 120 |
| 4 | 330 |
| 5 | 6336 |
| 6 | 61776 |
| 7 | 785928 |
| 8 | 10456875 |
| 9 | 151099520 |
| 10 | 2339361024 |
| 11 | 38655753552 |
| 12 | 678721170036 |
| 13 | 12615988058880 |
| 14 | 247449420044640 |
| 15 | 5106608041235184 |
| 16 | 110596074738524661 |
| 17 | 2507849090860975488 |