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 | 2 |
| 4 | 8 |
| 5 | 42 |
| 6 | 256 |
| 7 | 1810 |
| 8 | 14568 |
| 9 | 131642 |
| 10 | 1320128 |
| 11 | 14551074 |
| 12 | 174879880 |
| 13 | 2276108362 |
| 14 | 31894886208 |
| 15 | 478775722802 |
| 16 | 7664993150696 |
| 17 | 130369025763930 |
| 18 | 2347604596782208 |
| 19 | 44619881467365442 |
| 20 | 892659329531868168 |
| 21 | 18750556523491299434 |
| 22 | 412601744979927877760 |
| 23 | 9491630163800726992722 |