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 | 3 |
| 2 | 7 |
| 3 | 9 |
| 4 | -21 |
| 5 | -207 |
| 6 | -911 |
| 7 | -2769 |
| 8 | -5213 |
| 9 | 2457 |
| 10 | 74997 |
| 11 | 400491 |
| 12 | 1409109 |
| 13 | 3323583 |
| 14 | 2219343 |
| 15 | -27453951 |
| 16 | -186624333 |
| 17 | -750905127 |
| 18 | -2088947819 |
| 19 | -2955863589 |
| 20 | 8506703569 |
| 21 | 86421384387 |
| 22 | 401183114163 |
| 23 | 1280139325101 |
| 24 | 2522745571021 |