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 | 4 |
| 2 | 28 |
| 3 | 288 |
| 4 | 3984 |
| 5 | 70080 |
| 6 | 1506240 |
| 7 | 38384640 |
| 8 | 1133072640 |
| 9 | 38038533120 |
| 10 | 1431213235200 |
| 11 | 59645279232000 |
| 12 | 2726781752217600 |
| 13 | 135661078090137600 |
| 14 | 7295806823277772800 |
| 15 | 421717409630060544000 |
| 16 | 26071235813929033728000 |
| 17 | 1716456412254215503872000 |
| 18 | 119894838461795743137792000 |