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 | -1 |
| 4 | -1 |
| 5 | 7 |
| 6 | 1 |
| 7 | -103 |
| 8 | 197 |
| 9 | 2143 |
| 10 | -11717 |
| 11 | -50245 |
| 12 | 700541 |
| 13 | 445297 |
| 14 | -46679363 |
| 15 | 145710035 |
| 16 | 3366506123 |
| 17 | -28627646249 |
| 18 | -232615347479 |
| 19 | 4589590326917 |
| 20 | 7797081908429 |
| 21 | -722997025420733 |
| 22 | 2790363142173367 |
| 23 | 112843029882305495 |
| 24 | -1235970846163474579 |
| 25 | -16017081358111849247 |