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 | 1 |
| 3 | 2 |
| 4 | 4 |
| 5 | 18 |
| 6 | 99 |
| 7 | 612 |
| 8 | 4376 |
| 9 | 35620 |
| 10 | 324965 |
| 11 | 3285270 |
| 12 | 36462924 |
| 13 | 440840358 |
| 14 | 5767387591 |
| 15 | 81184266632 |
| 16 | 1223531387056 |
| 17 | 19657686459528 |
| 18 | 335404201199049 |
| 19 | 6056933308042410 |
| 20 | 115417137054004820 |
| 21 | 2314399674388138810 |
| 22 | 48717810299204919851 |
| 23 | 1074106226256896375532 |