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 | 3 |
| 5 | 24 |
| 6 | 136 |
| 7 | 612 |
| 8 | 2619 |
| 9 | 10480 |
| 10 | 41388 |
| 11 | 159780 |
| 12 | 614058 |
| 13 | 2341920 |
| 14 | 8919816 |
| 15 | 33905188 |
| 16 | 128907279 |
| 17 | 490213680 |
| 18 | 1866127840 |
| 19 | 7111777860 |
| 20 | 27140369148 |
| 21 | 103721218000 |
| 22 | 396974781456 |
| 23 | 1521577377012 |
| 24 | 5840547488954 |