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 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 2 |
| 6 | 56 |
| 7 | 0 |
| 8 | 4 |
| 9 | 374 |
| 10 | 14980 |
| 11 | 0 |
| 12 | 8 |
| 13 | 2664 |
| 14 | 302844 |
| 15 | 19005336 |
| 16 | 0 |
| 17 | 12 |
| 18 | 17556 |
| 19 | 6530656 |
| 20 | 1248702804 |
| 21 | 278982789260 |
| 22 | 0 |
| 23 | 18 |
| 24 | 121838 |
| 25 | 151793054 |