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) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 3 |
| 4 | 4 |
| 5 | 0 |
| 6 | 1 |
| 7 | 63 |
| 8 | 64 |
| 9 | -1320 |
| 10 | -1319 |
| 11 | 49203 |
| 12 | 49204 |
| 13 | -2653560 |
| 14 | -2653559 |
| 15 | 196707423 |
| 16 | 196707424 |
| 17 | -19194804720 |
| 18 | -19194804719 |
| 19 | 2385684870723 |
| 20 | 2385684870724 |
| 21 | -367985503366800 |
| 22 | -367985503366799 |
| 23 | 68980888889771103 |
| 24 | 68980888889771104 |
| 25 | -15445553274667315800 |