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 | 6 |
| 4 | 0 |
| 5 | 0 |
| 6 | 360 |
| 7 | 0 |
| 8 | 0 |
| 9 | 60480 |
| 10 | 0 |
| 11 | 0 |
| 12 | 19958400 |
| 13 | 0 |
| 14 | 0 |
| 15 | 10897286400 |
| 16 | 0 |
| 17 | 0 |
| 18 | 8892185702400 |
| 19 | 0 |
| 20 | 0 |
| 21 | 10137091700736000 |
| 22 | 0 |
| 23 | 0 |
| 24 | 15388105201717248000 |
| 25 | 0 |
| 26 | 0 |
| 27 | 30006805143348633600000 |
| 28 | 0 |
| 29 | 0 |
| 30 | 73096577329197271449600000 |