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 | 4 |
| 4 | -5 |
| 5 | 1 |
| 6 | 64 |
| 7 | -84 |
| 8 | 21 |
| 9 | -1 |
| 10 | 4096 |
| 11 | -5440 |
| 12 | 1428 |
| 13 | -85 |
| 14 | 1 |
| 15 | 1048576 |
| 16 | -1396736 |
| 17 | 371008 |
| 18 | -23188 |
| 19 | 341 |
| 20 | -1 |
| 21 | 1073741824 |
| 22 | -1431306240 |
| 23 | 381308928 |
| 24 | -24115520 |
| 25 | 372372 |
| 26 | -1365 |
| 27 | 1 |
| 28 | 4398046511104 |
| 29 | -5863704100864 |
| 30 | 1563272675328 |
| 31 | -99158478848 |