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 | 1 |
| 4 | 4 |
| 5 | 20 |
| 6 | 160 |
| 7 | 910 |
| 8 | 5936 |
| 9 | 53424 |
| 10 | 397440 |
| 11 | 3304620 |
| 12 | 35023120 |
| 13 | 322852816 |