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 | 20 |
| 5 | 51 |
| 6 | 2604 |
| 7 | 6665 |
| 8 | 720600 |
| 9 | 1864135 |
| 10 | 348678440 |
| 11 | 909090909 |
| 12 | 261535698060 |
| 13 | 685853880635 |
| 14 | 281241170407092 |
| 15 | 740800455037201 |
| 16 | 410525522232055664 |
| 17 | 1085102592571150095 |
| 18 | 781282469559318055056 |
| 19 | 2070863582910344082917 |
| 20 | 1879498672877297909667780 |
| 21 | 4993219047619047619047619 |
| 22 | 5577014881186619679500164220 |