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 | 0 |
| 1 | -1 |
| 2 | 26 |
| 3 | -486 |
| 4 | 8775 |
| 5 | -157600 |
| 6 | 2828384 |
| 7 | -50754249 |
| 8 | 910750554 |
| 9 | -16342762150 |
| 10 | 293258984975 |
| 11 | -5262319011456 |
| 12 | 94428483336576 |
| 13 | -1694450381348881 |
| 14 | 30405678381733850 |
| 15 | -545607760491930150 |
| 16 | 9790534010478427479 |
| 17 | -175684004428133950624 |
| 18 | 3152521545695969823584 |
| 19 | -56569703818099420107225 |