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 | -1 |
| 2 | 2 |
| 3 | -4 |
| 4 | 7 |
| 5 | -11 |
| 6 | 16 |
| 7 | -22 |
| 8 | 28 |
| 9 | -30 |
| 10 | 18 |
| 11 | 29 |
| 12 | -152 |
| 13 | 427 |
| 14 | -988 |
| 15 | 2060 |
| 16 | -4002 |
| 17 | 7354 |
| 18 | -12868 |
| 19 | 21472 |
| 20 | -34054 |
| 21 | 50838 |
| 22 | -69920 |
| 23 | 84186 |
| 24 | -75275 |
| 25 | 2395 |
| 26 | 217417 |
| 27 | -742554 |
| 28 | 1860191 |
| 29 | -4067099 |
| 30 | 8183154 |
| 31 | -15493168 |
| 32 | 27886577 |
| 33 | -47905049 |
| 34 | 78485095 |
| 35 | -121944988 |
| 36 | 177329498 |
| 37 | -234464309 |
| 38 | 261801461 |
| 39 | -183121605 |
| 40 | -164852147 |