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 | 0 |
| 2 | 14 |
| 3 | 0 |
| 4 | 546 |
| 5 | 0 |
| 6 | 32900 |
| 7 | 10080 |
| 8 | 2570050 |
| 9 | 2540160 |
| 10 | 238935564 |
| 11 | 465696000 |
| 12 | 25142196156 |
| 13 | 76886409600 |
| 14 | 2900343069624 |
| 15 | 12211317518400 |
| 16 | 359067702643650 |
| 17 | 1915829643087360 |
| 18 | 47006105030584700 |
| 19 | 300455419743198720 |
| 20 | 6437718469449262996 |