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 | 14 |
| 2 | 126 |
| 3 | 896 |
| 4 | 5488 |
| 5 | 30240 |
| 6 | 153888 |
| 7 | 735744 |
| 8 | 3344544 |
| 9 | 14581952 |
| 10 | 61378240 |
| 11 | 250693632 |
| 12 | 997593856 |
| 13 | 3880249856 |
| 14 | 14791776768 |
| 15 | 55385874432 |
| 16 | 204082373376 |
| 17 | 741186464256 |
| 18 | 2656771815936 |
| 19 | 9410113241088 |