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) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 1 |
| 5 | 2 |
| 6 | 13 |
| 7 | 50 |
| 8 | 221 |
| 9 | 866 |
| 10 | 3437 |
| 11 | 13250 |
| 12 | 51075 |
| 13 | 194810 |
| 14 | 742651 |
| 15 | 2823766 |
| 16 | 10738881 |
| 17 | 40843370 |
| 18 | 155494751 |
| 19 | 592614050 |
| 20 | 2261625725 |
| 21 | 8643289534 |
| 22 | 33080920607 |
| 23 | 126797503250 |
| 24 | 486710971595 |
| 25 | 1870851589554 |
| 26 | 7201014763285 |
| 27 | 27752927359726 |
| 28 | 107092397450897 |