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 | -2 |
| 2 | -32 |
| 3 | 256 |
| 4 | -8192 |
| 5 | -262144 |
| 6 | 5242880 |
| 7 | -33554432 |
| 8 | -2684354560 |
| 9 | 8589934592000 |
| 10 | 932385860354048 |
| 11 | 160159261748363264 |
| 12 | -1125899906842624 |
| 13 | -225179981368524800 |
| 14 | 5260204364768739328 |
| 15 | 43977037871723571052544 |