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 | 54 |
| 2 | 1620 |
| 3 | 35640 |
| 4 | 641520 |
| 5 | 10007712 |
| 6 | 140107968 |
| 7 | 1801388160 |
| 8 | 21616657920 |
| 9 | 244988789760 |
| 10 | 2645878929408 |
| 11 | 27420927086592 |
| 12 | 274209270865920 |
| 13 | 2657720625315840 |
| 14 | 25058508752977920 |
| 15 | 230538280527396864 |
| 16 | 2074844524746571776 |
| 17 | 18307451688940339200 |
| 18 | 158664581304149606400 |