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 | 1 |
| 3 | 5 |
| 4 | 2 |
| 5 | 26 |
| 6 | 6 |
| 7 | 186 |
| 8 | 18 |
| 9 | 1518 |
| 10 | 17070 |
| 11 | 14970 |
| 12 | 205050 |
| 13 | 177330 |
| 14 | 2873010 |
| 15 | 43515570 |
| 16 | 696699570 |
| 17 | 696219090 |
| 18 | 12540622290 |
| 19 | 12531433110 |
| 20 | 250812956310 |