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 | 0 |
| 1 | 1 |
| 2 | 6 |
| 3 | 33 |
| 4 | 208 |
| 5 | 1545 |
| 6 | 13326 |
| 7 | 130921 |
| 8 | 1441728 |
| 9 | 17572113 |
| 10 | 234662230 |
| 11 | 3405357681 |
| 12 | 53334454416 |
| 13 | 896324308633 |
| 14 | 16083557845278 |
| 15 | 306827170866105 |
| 16 | 6199668952527616 |
| 17 | 132240988644215841 |
| 18 | 2968971263911288998 |
| 19 | 69974827707903049153 |
| 20 | 1727194482044146637520 |
| 21 | 44552237162692939114281 |