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 | 0 |
| 5 | 27 |
| 6 | 21792 |
| 7 | 3324193 |
| 8 | 119138166 |
| 9 | 1979541332 |
| 10 | 20142680752 |
| 11 | 145977165234 |
| 12 | 824771174978 |
| 13 | 3850985758339 |
| 14 | 15461577137802 |
| 15 | 54912339921707 |
| 16 | 176153338628674 |
| 17 | 518569625849418 |
| 18 | 1418340918023792 |
| 19 | 3639736652346172 |
| 20 | 8833161922947702 |
| 21 | 20405252721413369 |