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 | -3 |
| 2 | 0 |
| 3 | 1 |
| 4 | -3 |
| 5 | 6 |
| 6 | -9 |
| 7 | 9 |
| 8 | 0 |
| 9 | -27 |
| 10 | 81 |
| 11 | -162 |
| 12 | 243 |
| 13 | -243 |
| 14 | 0 |
| 15 | 729 |
| 16 | -2187 |
| 17 | 4375 |
| 18 | -6579 |
| 19 | 6732 |
| 20 | -1139 |
| 21 | -13719 |
| 22 | 32946 |
| 23 | -18921 |
| 24 | -158355 |
| 25 | 851598 |
| 26 | -2896919 |
| 27 | 8097219 |
| 28 | -20058300 |
| 29 | 45540943 |
| 30 | -96506229 |
| 31 | 193012458 |
| 32 | -367077447 |
| 33 | 667617642 |
| 34 | -1166803109 |
| 35 | 1968991969 |
| 36 | -3225375252 |