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 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 6 |
| 4 | 46 |
| 5 | 636 |
| 6 | 10527 |
| 7 | 194997 |
| 8 | 3823327 |
| 9 | 78118107 |
| 10 | 1646300388 |
| 11 | 35570427615 |
| 12 | 784467060622 |
| 13 | 17601062294302 |
| 14 | 400750115756742 |
| 15 | 9240636709048733 |
| 16 | 215435023547580882 |
| 17 | 5071520482516388865 |
| 18 | 120417032326341878672 |
| 19 | 2881134828445365441407 |
| 20 | 69410468220307148620226 |