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 | 4 |
| 4 | 126 |
| 5 | 9367 |
| 6 | 1120780 |
| 7 | 189565588 |
| 8 | 43154533233 |
| 9 | 12735808866899 |
| 10 | 4732638168795171 |
| 11 | 2163220895025390670 |
| 12 | 1193176166690983987122 |
| 13 | 781607533669746761791541 |