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 | 0 |
| 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 | 105840 |
| 20 | -201684 |
| 21 | 364609 |
| 22 | -618772 |
| 23 | 964173 |
| 24 | -1309574 |
| 25 | 1309574 |
| 26 | 1 |
| 27 | -4970097 |
| 28 | 18874639 |
| 29 | -52835258 |
| 30 | 129107566 |
| 31 | -290081057 |
| 32 | 612479308 |
| 33 | -1227418279 |
| 34 | 2343572690 |
| 35 | -4261482736 |