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 | -6 |
| 4 | 14 |
| 5 | -32 |
| 6 | 76 |
| 7 | -180 |
| 8 | 424 |
| 9 | -1000 |
| 10 | 2360 |
| 11 | -5568 |
| 12 | 13136 |
| 13 | -30992 |
| 14 | 73120 |
| 15 | -172512 |
| 16 | 407008 |
| 17 | -960256 |
| 18 | 2265536 |
| 19 | -5345088 |
| 20 | 12610688 |
| 21 | -29752448 |
| 22 | 70195072 |
| 23 | -165611520 |
| 24 | 390727936 |
| 25 | -921846016 |
| 26 | 2174915072 |
| 27 | -5131286016 |
| 28 | 12106264064 |
| 29 | -28562358272 |
| 30 | 67387288576 |
| 31 | -158987105280 |