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 | 0 |
| 3 | 0 |
| 4 | 2 |
| 5 | 10 |
| 6 | 4 |
| 7 | 28 |
| 8 | 20 |
| 9 | 56 |
| 10 | 72 |
| 11 | 200 |
| 12 | 644 |
| 13 | 2940 |
| 14 | 9152 |
| 15 | 39200 |
| 16 | 166100 |
| 17 | 739924 |
| 18 | 3586840 |
| 19 | 18640500 |
| 20 | 107580592 |
| 21 | 547737844 |
| 22 | 3080550788 |