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 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 20 |
| 5 | 80 |
| 6 | 384 |
| 7 | 2112 |
| 8 | 12992 |
| 9 | 94272 |
| 10 | 716800 |
| 11 | 6141440 |
| 12 | 58451568 |
| 13 | 596647568 |
| 14 | 6555879072 |
| 15 | 77766001056 |
| 16 | 981202169600 |