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 | 0 |
| 4 | 15 |
| 5 | 6 |
| 6 | 87 |
| 7 | 84 |
| 8 | 567 |
| 9 | 882 |
| 10 | 4095 |
| 11 | 8448 |
| 12 | 32079 |
| 13 | 78078 |
| 14 | 265863 |
| 15 | 710892 |
| 16 | 2282631 |
| 17 | 6430794 |
| 18 | 20009391 |
| 19 | 58008216 |
| 20 | 177478623 |
| 21 | 522598230 |
| 22 | 1584540279 |
| 23 | 4705481220 |
| 24 | 14198074455 |
| 25 | 42357719586 |
| 26 | 127472924127 |
| 27 | 381253030704 |