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 | 2 |
| 2 | 4 |
| 3 | 16 |
| 4 | 96 |
| 5 | 768 |
| 6 | 7680 |
| 7 | 92160 |
| 8 | 1290240 |
| 9 | 20643840 |
| 10 | 371589120 |
| 11 | 7431782400 |
| 12 | 163499212800 |
| 13 | 3923981107200 |
| 14 | 102023508787200 |
| 15 | 2856658246041600 |
| 16 | 85699747381248000 |
| 17 | 2742391916199936000 |
| 18 | 93241325150797824000 |
| 19 | 3356687705428721664000 |
| 20 | 127554132806291423232000 |