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 | 1 |
| 2 | 0 |
| 3 | 0 |
| 4 | 1 |
| 5 | 1 |
| 6 | 5 |
| 7 | 19 |
| 8 | 76 |
| 9 | 360 |
| 10 | 1792 |
| 11 | 9634 |
| 12 | 55286 |
| 13 | 336396 |
| 14 | 2162554 |
| 15 | 14629720 |
| 16 | 103818489 |
| 17 | 770678553 |
| 18 | 5969822993 |
| 19 | 48148947503 |
| 20 | 403545713463 |
| 21 | 3508356996105 |
| 22 | 31587389832791 |
| 23 | 294087418038113 |
| 24 | 2827471212909189 |
| 25 | 28037001032306431 |
| 26 | 286398141349873925 |
| 27 | 3010540174760962975 |