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) |
|---|---|
| 0 | 0 |
| 1 | 6 |
| 2 | 36 |
| 3 | 210 |
| 4 | 1224 |
| 5 | 7134 |
| 6 | 41580 |
| 7 | 242346 |
| 8 | 1412496 |
| 9 | 8232630 |
| 10 | 47983284 |
| 11 | 279667074 |
| 12 | 1630019160 |
| 13 | 9500447886 |
| 14 | 55372668156 |
| 15 | 322735561050 |
| 16 | 1881040698144 |
| 17 | 10963508627814 |
| 18 | 63900011068740 |
| 19 | 372436557784626 |
| 20 | 2170719335639016 |