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 | 760 |
| 3 | 0 |
| 4 | 77560 |
| 5 | 524288 |
| 6 | 2508000 |
| 7 | 10485760 |
| 8 | 34729720 |
| 9 | 99614720 |
| 10 | 259114704 |
| 11 | 608174080 |
| 12 | 1327461600 |
| 13 | 2739404800 |
| 14 | 5341699520 |
| 15 | 9921626112 |
| 16 | 17701924600 |
| 17 | 30592204800 |
| 18 | 51294999960 |
| 19 | 83277905920 |
| 20 | 131880275664 |