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 | 0 |
| 2 | -1 |
| 3 | 1 |
| 4 | 2 |
| 5 | -6 |
| 6 | -1 |
| 7 | 28 |
| 8 | -31 |
| 9 | -98 |
| 10 | 288 |
| 11 | 131 |
| 12 | -1730 |
| 13 | 1638 |
| 14 | 7431 |
| 15 | -19583 |
| 16 | -15502 |
| 17 | 135642 |
| 18 | -99523 |
| 19 | -664050 |
| 20 | 1535896 |
| 21 | 1816196 |
| 22 | -11902728 |
| 23 | 5944326 |
| 24 | 64487669 |
| 25 | -129346490 |
| 26 | -213116764 |
| 27 | 1112382523 |
| 28 | -277762230 |
| 29 | -6572175490 |
| 30 | 11287106695 |
| 31 | 25078981772 |
| 32 | -107983368519 |
| 33 | -1826241850 |