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 | -1 |
| 3 | 1 |
| 4 | -5 |
| 5 | 4 |
| 6 | 1 |
| 7 | -21 |
| 8 | 72 |
| 9 | -52 |
| 10 | 1 |
| 11 | -85 |
| 12 | 1020 |
| 13 | -3016 |
| 14 | 2080 |
| 15 | 1 |
| 16 | -341 |
| 17 | 13600 |
| 18 | -133900 |
| 19 | 372320 |
| 20 | -251680 |
| 21 | 1 |
| 22 | -1365 |
| 23 | 178164 |
| 24 | -5532800 |
| 25 | 50406720 |
| 26 | -136662240 |
| 27 | 91611520 |
| 28 | 1 |
| 29 | -5461 |
| 30 | 2321592 |
| 31 | -223628132 |
| 32 | 6320525120 |
| 33 | -55844268480 |
| 34 | 149876446720 |
| 35 | -100131391360 |