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 | 3 |
| 3 | 20 |
| 4 | 56 |
| 5 | 576 |
| 6 | 1408 |
| 7 | 6656 |
| 8 | 5120 |
| 9 | 278528 |
| 10 | 622592 |
| 11 | 2752512 |
| 12 | 6029312 |
| 13 | 52428800 |
| 14 | 113246208 |
| 15 | 486539264 |
| 16 | 1040187392 |
| 17 | 11811160064 |
| 18 | 15032385536 |
| 19 | 317827579904 |
| 20 | 223338299392 |
| 21 | 5634997092352 |
| 22 | 11819749998592 |
| 23 | 3298534883328 |