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 | 5 |
| 2 | 0 |
| 3 | -125 |
| 4 | 625 |
| 5 | 5625 |
| 6 | -87500 |
| 7 | 0 |
| 8 | 9140625 |
| 9 | -60156250 |
| 10 | -653125000 |
| 11 | 11654296875 |
| 12 | 0 |
| 13 | -1470068359375 |
| 14 | 10353515625000 |
| 15 | 118916992187500 |
| 16 | -2225148925781250 |
| 17 | 0 |
| 18 | 302784667968750000 |
| 19 | -2199076690673828125 |
| 20 | -25952287445068359375 |
| 21 | 497460246276855468750 |
| 22 | 0 |