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 | 1 |
| 2 | 4 |
| 3 | 12 |
| 4 | 128 |
| 5 | -2360 |
| 6 | 225504 |
| 7 | -31479056 |
| 8 | 7663698176 |
| 9 | -3268091071872 |
| 10 | 2502155367185920 |
| 11 | -3525130171601665792 |
| 12 | 9336272433375180957696 |
| 13 | -47283253230423958235278336 |
| 14 | 463782058088334028985937178624 |
| 15 | -8890882429150197015851583349985280 |