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) |
|---|---|
| 2 | -2 |
| 3 | -8 |
| 4 | -16 |
| 5 | 0 |
| 6 | 160 |
| 7 | 896 |
| 8 | 3584 |
| 9 | 12288 |
| 10 | 38400 |
| 11 | 112640 |
| 12 | 315392 |
| 13 | 851968 |
| 14 | 2236416 |
| 15 | 5734400 |
| 16 | 14417920 |
| 17 | 35651584 |
| 18 | 86900736 |
| 19 | 209190912 |
| 20 | 498073600 |
| 21 | 1174405120 |
| 22 | 2745171968 |
| 23 | 6366953472 |
| 24 | 14663286784 |
| 25 | 33554432000 |
| 26 | 76336332800 |
| 27 | 172738215936 |