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 | 144 |
| 1 | 0 |
| 2 | 864 |
| 3 | 1764 |
| 4 | 3168 |
| 5 | 18468 |
| 6 | 25200 |
| 7 | 117612 |
| 8 | 301104 |
| 9 | 736164 |
| 10 | 3083472 |
| 11 | 7009200 |
| 12 | 26587584 |
| 13 | 75949200 |
| 14 | 220443768 |
| 15 | 728295840 |
| 16 | 1994796720 |
| 17 | 6533132760 |
| 18 | 19485485712 |
| 19 | 59845160592 |
| 20 | 189326190240 |
| 21 | 566841960000 |