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 | 4 |
| 3 | 6 |
| 4 | 36 |
| 5 | 100 |
| 6 | 430 |
| 7 | 1470 |
| 8 | 5796 |
| 9 | 21336 |
| 10 | 82404 |
| 11 | 312180 |
| 12 | 1203246 |
| 13 | 4617756 |
| 14 | 17846686 |
| 15 | 68974906 |
| 16 | 267498660 |
| 17 | 1038555024 |
| 18 | 4040525320 |
| 19 | 15739195680 |
| 20 | 61399048036 |
| 21 | 239788778760 |
| 22 | 937536139764 |
| 23 | 3669179504364 |
| 24 | 14373144873774 |
| 25 | 56350223472600 |
| 26 | 221094286028100 |