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 | 4 |
| 4 | 22 |
| 5 | 241 |
| 6 | 2696 |
| 7 | 35218 |
| 8 | 529888 |
| 9 | 8998419 |
| 10 | 169486964 |
| 11 | 3496417024 |
| 12 | 78344008779 |
| 13 | 1891733424205 |
| 14 | 48923563968087 |
| 15 | 1347813311456319 |
| 16 | 39371345548420060 |
| 17 | 1214570579814316742 |
| 18 | 39430967625404799740 |
| 19 | 1343040950675651131103 |
| 20 | 47862610677098010505554 |