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 | 1 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 2 |
| 5 | 0 |
| 6 | 4 |
| 7 | 4 |
| 8 | 6 |
| 9 | 24 |
| 10 | 24 |
| 11 | 68 |
| 12 | 190 |
| 13 | 192 |
| 14 | 904 |
| 15 | 1420 |
| 16 | 3106 |
| 17 | 9940 |
| 18 | 14572 |
| 19 | 49268 |
| 20 | 102886 |
| 21 | 225004 |
| 22 | 652940 |
| 23 | 1301256 |
| 24 | 3513806 |
| 25 | 8591792 |
| 26 | 19326248 |
| 27 | 52781148 |
| 28 | 120709472 |
| 29 | 306339824 |
| 30 | 779682608 |
| 31 | 1852672272 |
| 32 | 4847112666 |
| 33 | 11876028924 |