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 | 3 |
| 1 | 0 |
| 2 | 6 |
| 3 | -3 |
| 4 | 18 |
| 5 | -15 |
| 6 | 57 |
| 7 | -63 |
| 8 | 186 |
| 9 | -246 |
| 10 | 621 |
| 11 | -924 |
| 12 | 2109 |
| 13 | -3393 |
| 14 | 7251 |
| 15 | -12288 |
| 16 | 25146 |
| 17 | -44115 |
| 18 | 87726 |
| 19 | -157491 |
| 20 | 307293 |
| 21 | -560199 |
| 22 | 1079370 |
| 23 | -1987890 |
| 24 | 3798309 |
| 25 | -7043040 |
| 26 | 13382817 |
| 27 | -24927429 |
| 28 | 47191491 |
| 29 | -88165104 |
| 30 | 166501902 |
| 31 | -311686803 |
| 32 | 587670810 |
| 33 | -1101562311 |