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 | 2 |
| 4 | 13 |
| 5 | 64 |
| 6 | 285 |
| 7 | 1210 |
| 8 | 5005 |
| 9 | 20384 |
| 10 | 82212 |
| 11 | 329460 |
| 12 | 1314610 |
| 13 | 5230016 |
| 14 | 20764055 |
| 15 | 82317690 |
| 16 | 326012925 |
| 17 | 1290244800 |
| 18 | 5103910680 |
| 19 | 20183646780 |
| 20 | 79802261190 |
| 21 | 315492902400 |
| 22 | 1247247742650 |
| 23 | 4930910180196 |
| 24 | 19495286167698 |
| 25 | 77085553829824 |
| 26 | 304836321995800 |
| 27 | 1205640294021800 |