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 | 1 |
| 4 | 6 |
| 5 | 41 |
| 6 | 274 |
| 7 | 2040 |
| 8 | 16346 |
| 9 | 143571 |
| 10 | 1365354 |
| 11 | 14056287 |
| 12 | 155638724 |
| 13 | 1847352720 |
| 14 | 23400880036 |
| 15 | 315270938501 |
| 16 | 4502081195166 |
| 17 | 67941159822229 |
| 18 | 1080528172834710 |
| 19 | 18065046986905320 |
| 20 | 316769071197428286 |
| 21 | 5813469963339136855 |
| 22 | 111449225620923739458 |