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) |
|---|---|
| 1 | 1 |
| 2 | 6 |
| 3 | 56 |
| 4 | 448 |
| 5 | 6264 |
| 6 | 96348 |
| 7 | 1559520 |
| 8 | 16908804 |
| 9 | 391945400 |
| 10 | 20553536052 |
| 11 | 706019328000 |
| 12 | 20210523379200 |
| 13 | 519285252355776 |
| 14 | 21710734431216480 |
| 15 | 1456143373228677120 |
| 16 | 25536237889612326912 |
| 17 | 1792353900753729655758 |
| 18 | 52839150354952425838080 |
| 19 | 4154723599066412190910560 |