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 | 0 |
| 2 | 1 |
| 3 | 1 |
| 4 | 13 |
| 5 | 12 |
| 6 | 324 |
| 7 | 1352 |
| 8 | 18368 |
| 9 | 19152 |
| 10 | 1994322 |
| 11 | 8810748 |
| 12 | 193690826 |
| 13 | 829046868 |
| 14 | 34563283272 |
| 15 | 274895151856 |
| 16 | 14554448767872 |
| 17 | 8178592487376 |
| 18 | 2493850026398472 |
| 19 | 33842416675133248 |
| 20 | 1037660717168380800 |
| 21 | 6072370562498569056 |
| 22 | 682597834324732589120 |
| 23 | 5390950170768906240000 |