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 | 1 |
| 5 | 15 |
| 6 | 11 |
| 7 | 201 |
| 8 | 561 |
| 9 | 4575 |
| 10 | 25171 |
| 11 | 187801 |
| 12 | 1400521 |
| 13 | 11694735 |
| 14 | 103903931 |
| 15 | 993285801 |
| 16 | 10113814881 |
| 17 | 109470594495 |
| 18 | 1254389104291 |
| 19 | 15173016742201 |
| 20 | 193187969483641 |
| 21 | 2582736821247855 |
| 22 | 36172850924874251 |