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 | 1 |
| 2 | 12 |
| 3 | 112 |
| 4 | 960 |
| 5 | 7936 |
| 6 | 64512 |
| 7 | 520192 |
| 8 | 4177920 |
| 9 | 33488896 |
| 10 | 268173312 |
| 11 | 2146435072 |
| 12 | 17175674880 |
| 13 | 137422176256 |
| 14 | 1099444518912 |
| 15 | 8795824586752 |
| 16 | 70367670435840 |
| 17 | 562945658454016 |
| 18 | 4503582447501312 |
| 19 | 36028728299487232 |