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 | 1 |
| 3 | -2 |
| 4 | 4 |
| 5 | -8 |
| 6 | 16 |
| 7 | -31 |
| 8 | 56 |
| 9 | -91 |
| 10 | 126 |
| 11 | -126 |
| 12 | 0 |
| 13 | 462 |
| 14 | -1715 |
| 15 | 4704 |
| 16 | -11319 |
| 17 | 25186 |
| 18 | -52920 |
| 19 | 105841 |
| 20 | -201704 |
| 21 | 364819 |
| 22 | -620312 |
| 23 | 973028 |
| 24 | -1352078 |
| 25 | 1486674 |
| 26 | -657799 |
| 27 | -2750022 |
| 28 | 11967739 |
| 29 | -32805248 |
| 30 | 74480266 |
| 31 | -148960531 |
| 32 | 265105676 |
| 33 | -408608551 |
| 34 | 487599186 |
| 35 | -201501426 |