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 | 0 |
| 1 | 4 |
| 2 | 256 |
| 3 | 5184 |
| 4 | 65536 |
| 5 | 640000 |
| 6 | 5308416 |
| 7 | 39337984 |
| 8 | 268435456 |
| 9 | 1719926784 |
| 10 | 10485760000 |
| 11 | 61408804864 |
| 12 | 347892350976 |
| 13 | 1916696264704 |
| 14 | 10312216477696 |
| 15 | 54358179840000 |
| 16 | 281474976710656 |
| 17 | 1434879854116864 |
| 18 | 7213895789838336 |
| 19 | 35822363710849024 |
| 20 | 175921860444160000 |
| 21 | 855336483526017024 |