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 | 7 |
| 2 | 50 |
| 3 | 366 |
| 4 | 2760 |
| 5 | 21576 |
| 6 | 176112 |
| 7 | 1512720 |
| 8 | 13781376 |
| 9 | 134110080 |
| 10 | 1401566976 |
| 11 | 15780033792 |
| 12 | 191537187840 |
| 13 | 2503044135936 |
| 14 | 35120982067200 |
| 15 | 527284915992576 |
| 16 | 8439379765788672 |
| 17 | 143486382677852160 |
| 18 | 2582856448158007296 |