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 | 2 |
| 2 | 8 |
| 3 | 40 |
| 4 | 212 |
| 5 | 1152 |
| 6 | 6360 |
| 7 | 35520 |
| 8 | 200132 |
| 9 | 1135456 |
| 10 | 6478088 |
| 11 | 37128896 |
| 12 | 213617704 |
| 13 | 1233014720 |
| 14 | 7136819376 |
| 15 | 41408161920 |
| 16 | 240758343684 |
| 17 | 1402436532576 |
| 18 | 8182797500328 |
| 19 | 47814708577728 |
| 20 | 279768031296312 |
| 21 | 1638915078384960 |
| 22 | 9611453035886160 |