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 | 6 |
| 2 | 30 |
| 3 | 180 |
| 4 | 1002 |
| 5 | 6012 |
| 6 | 34224 |
| 7 | 205344 |
| 8 | 1180010 |
| 9 | 7080060 |
| 10 | 40911324 |
| 11 | 245467944 |
| 12 | 1423944024 |
| 13 | 8543664144 |
| 14 | 49710351720 |
| 15 | 298262110320 |
| 16 | 1739627237002 |
| 17 | 10437763422012 |
| 18 | 61002039226716 |
| 19 | 366012235360296 |
| 20 | 2142786218045748 |
| 21 | 12856717308274488 |
| 22 | 75380119335678608 |