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 | -7 |
| 3 | -43 |
| 4 | 245 |
| 5 | 4045 |
| 6 | -20795 |
| 7 | -729335 |
| 8 | 3118985 |
| 9 | 217496825 |
| 10 | -667140175 |
| 11 | -97338843875 |
| 12 | 149451128125 |
| 13 | 61156245509125 |
| 14 | 18055448952125 |
| 15 | -51399370203595375 |
| 16 | -123577855227019375 |
| 17 | 55722247285947360625 |
| 18 | 266112415762709595625 |
| 19 | -75739843360243364046875 |
| 20 | -560236984557463079546875 |