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 | 3 |
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | -9 |
| 7 | 0 |
| 8 | 27 |
| 9 | 0 |
| 10 | 0 |
| 11 | 0 |
| 12 | -324 |
| 13 | 0 |
| 14 | 1215 |
| 15 | 0 |
| 16 | 0 |
| 17 | 0 |
| 18 | -18711 |
| 19 | 0 |
| 20 | 75816 |
| 21 | 0 |
| 22 | 0 |
| 23 | 0 |
| 24 | -1301265 |
| 25 | 0 |
| 26 | 5484996 |
| 27 | 0 |
| 28 | 0 |
| 29 | 0 |
| 30 | -100048689 |
| 31 | 0 |
| 32 | 431943435 |
| 33 | 0 |
| 34 | 0 |
| 35 | 0 |
| 36 | -8192222064 |
| 37 | 0 |
| 38 | 35942240565 |
| 39 | 0 |
| 40 | 0 |
| 41 | 0 |
| 42 | -700434986472 |
| 43 | 0 |
| 44 | 3108770417700 |
| 45 | 0 |
| 46 | 0 |
| 47 | 0 |
| 48 | -61805774132388 |
| 49 | 0 |
| 50 | 276711654879477 |