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 | 5 |
| 5 | 23 |
| 6 | 123 |
| 7 | 788 |
| 8 | 5853 |
| 9 | 49330 |
| 10 | 465113 |
| 11 | 4850460 |
| 12 | 55433829 |
| 13 | 688963306 |
| 14 | 9251792972 |
| 15 | 133490155744 |
| 16 | 2059562402903 |
| 17 | 33835668047686 |
| 18 | 589707357402530 |
| 19 | 10867464157846630 |
| 20 | 211139303638163097 |
| 21 | 4313274345751046120 |