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 | 0 |
| 1 | 1 |
| 2 | 0 |
| 3 | 0 |
| 4 | -1 |
| 5 | 0 |
| 6 | 0 |
| 7 | 4 |
| 8 | 0 |
| 9 | -1 |
| 10 | -22 |
| 11 | 0 |
| 12 | 13 |
| 13 | 140 |
| 14 | 0 |
| 15 | -136 |
| 16 | -970 |
| 17 | 9 |
| 18 | 1330 |
| 19 | 7104 |
| 20 | -231 |
| 21 | -12650 |
| 22 | -54096 |
| 23 | 3900 |
| 24 | 118780 |
| 25 | 423890 |
| 26 | -54810 |
| 27 | -1108380 |
| 28 | -3393696 |
| 29 | 695640 |
| 30 | 10311840 |
| 31 | 27615648 |
| 32 | -8282604 |
| 33 | -95810606 |
| 34 | -227480848 |
| 35 | 94449456 |
| 36 | 889817328 |
| 37 | 1890685212 |
| 38 | -1044402840 |
| 39 | -8263944216 |
| 40 | -15811484852 |