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 | 1 |
| 3 | 0 |
| 4 | 0 |
| 5 | 5 |
| 6 | 5 |
| 7 | -56 |
| 8 | -56 |
| 9 | 1329 |
| 10 | 1329 |
| 11 | -49192 |
| 12 | -49192 |
| 13 | 2653573 |
| 14 | 2653573 |
| 15 | -196707408 |
| 16 | -196707408 |
| 17 | 19194804737 |
| 18 | 19194804737 |
| 19 | -2385684870704 |
| 20 | -2385684870704 |
| 21 | 367985503366821 |
| 22 | 367985503366821 |
| 23 | -68980888889771080 |
| 24 | -68980888889771080 |