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 | 2 |
| 2 | 3 |
| 3 | 4 |
| 4 | 4 |
| 5 | 0 |
| 6 | -16 |
| 7 | -64 |
| 8 | -192 |
| 9 | -512 |
| 10 | -1280 |
| 11 | -3072 |
| 12 | -7168 |
| 13 | -16384 |
| 14 | -36864 |
| 15 | -81920 |
| 16 | -180224 |
| 17 | -393216 |
| 18 | -851968 |
| 19 | -1835008 |
| 20 | -3932160 |
| 21 | -8388608 |
| 22 | -17825792 |
| 23 | -37748736 |
| 24 | -79691776 |
| 25 | -167772160 |
| 26 | -352321536 |
| 27 | -738197504 |
| 28 | -1543503872 |
| 29 | -3221225472 |
| 30 | -6710886400 |