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 | 0 |
| 7 | 0 |
| 8 | 0 |
| 9 | 40 |
| 10 | 52 |
| 11 | 152 |
| 12 | 260 |
| 13 | 1192 |
| 14 | 4144 |
| 15 | 18408 |
| 16 | 71552 |
| 17 | 312936 |
| 18 | 1498156 |
| 19 | 7854672 |
| 20 | 44923706 |
| 21 | 213840604 |
| 22 | 1156549592 |