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 | -5 |
| 4 | 10 |
| 5 | -20 |
| 6 | 35 |
| 7 | -50 |
| 8 | 50 |
| 9 | 0 |
| 10 | -175 |
| 11 | 625 |
| 12 | -1625 |
| 13 | 3625 |
| 14 | -7250 |
| 15 | 13125 |
| 16 | -21250 |
| 17 | 29375 |
| 18 | -29375 |
| 19 | 0 |
| 20 | 106250 |
| 21 | -384375 |
| 22 | 1006250 |
| 23 | -2250000 |
| 24 | 4500000 |
| 25 | -8140625 |
| 26 | 13171875 |
| 27 | -18203125 |
| 28 | 18203125 |
| 29 | 0 |
| 30 | -65859375 |
| 31 | 238281250 |
| 32 | -623828125 |
| 33 | 1394921875 |
| 34 | -2789843750 |
| 35 | 5046875000 |
| 36 | -8166015625 |