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 | 2 |
| 5 | 16 |
| 6 | 96 |
| 7 | 510 |
| 8 | 2558 |
| 9 | 12282 |
| 10 | 57498 |
| 11 | 263421 |
| 12 | 1192480 |
| 13 | 5330078 |
| 14 | 23657520 |
| 15 | 104106655 |
| 16 | 455993276 |
| 17 | 1984733843 |
| 18 | 8609546380 |
| 19 | 37164674383 |