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) |
|---|---|
| 5 | 2 |
| 6 | 24 |
| 7 | 140 |
| 8 | 1232 |
| 9 | 11268 |
| 10 | 115056 |
| 11 | 1284360 |
| 12 | 15596208 |
| 13 | 204710454 |
| 14 | 2888897032 |
| 15 | 43625578836 |
| 16 | 702025263328 |
| 17 | 11993721979336 |
| 18 | 216822550325472 |
| 19 | 4135337882588880 |
| 20 | 82986434235959712 |
| 21 | 1747976804189353962 |
| 22 | 38559791049947726328 |
| 23 | 889047923669760546140 |