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 | -7 |
| 4 | 9 |
| 5 | 9 |
| 6 | 49 |
| 7 | -176 |
| 8 | 57 |
| 9 | -673 |
| 10 | 2401 |
| 11 | 1143 |
| 12 | -9063 |
| 13 | 33201 |
| 14 | -153502 |
| 15 | 315783 |
| 16 | -755943 |
| 17 | 2210985 |
| 18 | -767039 |
| 19 | 1790369 |
| 20 | -40127031 |
| 21 | 44496424 |
| 22 | -58813391 |
| 23 | 1040502519 |
| 24 | -1696965207 |
| 25 | -1810005816 |
| 26 | -4483997699 |
| 27 | 7445790947 |
| 28 | 105920054242 |
| 29 | -134133273672 |
| 30 | -203398909151 |