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 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 3 |
| 5 | 140 |
| 6 | 1125 |
| 7 | 5355 |
| 8 | 19075 |
| 9 | 56133 |
| 10 | 143955 |
| 11 | 332475 |
| 12 | 706860 |
| 13 | 1404975 |
| 14 | 2640638 |
| 15 | 4733820 |
| 16 | 8149050 |
| 17 | 13543390 |
| 18 | 21825450 |
| 19 | 34227018 |
| 20 | 52388985 |
| 21 | 78463350 |
| 22 | 115233195 |
| 23 | 166252625 |
| 24 | 236008773 |
| 25 | 330108075 |
| 26 | 455489125 |
| 27 | 620664525 |
| 28 | 835994250 |