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) |
|---|---|
| 4 | 1 |
| 5 | 9 |
| 6 | 54 |
| 7 | 273 |
| 8 | 1260 |
| 9 | 5508 |
| 10 | 23256 |
| 11 | 95931 |
| 12 | 389367 |
| 13 | 1562275 |
| 14 | 6216210 |
| 15 | 24582285 |
| 16 | 96768360 |
| 17 | 379629720 |
| 18 | 1485507600 |
| 19 | 5801732460 |
| 20 | 22626756594 |
| 21 | 88152205554 |
| 22 | 343176898988 |
| 23 | 1335293573130 |
| 24 | 5193831553416 |
| 25 | 20198233818840 |
| 26 | 78542105700240 |
| 27 | 305417807763705 |