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 | 2 |
| 2 | 20 |
| 3 | 160 |
| 4 | 1200 |
| 5 | 8800 |
| 6 | 64000 |
| 7 | 464000 |
| 8 | 3360000 |
| 9 | 24320000 |
| 10 | 176000000 |
| 11 | 1273600000 |
| 12 | 9216000000 |
| 13 | 66688000000 |
| 14 | 482560000000 |
| 15 | 3491840000000 |
| 16 | 25267200000000 |
| 17 | 182835200000000 |
| 18 | 1323008000000000 |
| 19 | 9573376000000000 |