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 | 10 |
| 6 | 44 |
| 7 | 168 |
| 8 | 636 |
| 9 | 2364 |
| 10 | 8984 |
| 11 | 34672 |
| 12 | 138104 |
| 13 | 564408 |
| 14 | 2382288 |
| 15 | 10333152 |
| 16 | 46173968 |
| 17 | 211733776 |
| 18 | 997182752 |
| 19 | 4809439296 |
| 20 | 23758139808 |
| 21 | 119951644320 |
| 22 | 618882541760 |
| 23 | 3257839688320 |
| 24 | 17492182188992 |
| 25 | 95680426983360 |