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 | 3 |
| 3 | 3 |
| 4 | 30 |
| 5 | 93 |
| 6 | 633 |
| 7 | 3342 |
| 8 | 22809 |
| 9 | 156063 |
| 10 | 1183872 |
| 11 | 9453711 |
| 12 | 80455125 |
| 13 | 721576560 |
| 14 | 6809391111 |
| 15 | 67332650007 |
| 16 | 695777512638 |
| 17 | 7493572404345 |
| 18 | 83926492573341 |
| 19 | 975467527353750 |
| 20 | 11744536832206149 |
| 21 | 146234590864310019 |
| 22 | 1880198749437144456 |
| 23 | 24928860500681953683 |