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 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 120 |
| 6 | 1080 |
| 7 | 6300 |
| 8 | 30240 |
| 9 | 130032 |
| 10 | 521640 |
| 11 | 1996500 |
| 12 | 7389360 |
| 13 | 26676936 |
| 14 | 94486392 |
| 15 | 329647500 |
| 16 | 1136116800 |
| 17 | 3876164832 |
| 18 | 13112135496 |
| 19 | 44031456900 |
| 20 | 146920942800 |
| 21 | 487489214520 |
| 22 | 1609441068312 |
| 23 | 5289755245500 |
| 24 | 17315399138400 |
| 25 | 56470807803600 |
| 26 | 183546483143400 |