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 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 128 |
| 5 | 120 |
| 6 | 30312 |
| 7 | 283906 |
| 8 | 1872064 |
| 9 | 8643186 |
| 10 | 31702920 |
| 11 | 98179400 |
| 12 | 267487920 |
| 13 | 659015500 |
| 14 | 1496908840 |
| 15 | 3179369070 |
| 16 | 6382030592 |
| 17 | 12207535134 |
| 18 | 22396355496 |
| 19 | 39617305308 |
| 20 | 67860021680 |