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 | 36 |
| 3 | 224 |
| 4 | 1440 |
| 5 | 9504 |
| 6 | 64064 |
| 7 | 439296 |
| 8 | 3055104 |
| 9 | 21498880 |
| 10 | 152807424 |
| 11 | 1095450624 |
| 12 | 7911587840 |
| 13 | 57511157760 |
| 14 | 420459724800 |
| 15 | 3089600348160 |
| 16 | 22806128885760 |
| 17 | 169033661153280 |
| 18 | 1257467341701120 |
| 19 | 9385880636620800 |
| 20 | 70271680244613120 |
| 21 | 527595313582571520 |