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 | 1 |
| 2 | -1 |
| 3 | -1 |
| 4 | 1 |
| 5 | 2 |
| 6 | -1 |
| 7 | -5 |
| 8 | -1 |
| 9 | 11 |
| 10 | 10 |
| 11 | -21 |
| 12 | -39 |
| 13 | 30 |
| 14 | 126 |
| 15 | 4 |
| 16 | -354 |
| 17 | -261 |
| 18 | 834 |
| 19 | 1347 |
| 20 | -1483 |
| 21 | -5033 |
| 22 | 823 |
| 23 | 15663 |
| 24 | 8765 |
| 25 | -41112 |
| 26 | -56364 |
| 27 | 84888 |
| 28 | 234546 |
| 29 | -91319 |
| 30 | -791833 |
| 31 | -293380 |
| 32 | 2251507 |
| 33 | 2561264 |
| 34 | -5177875 |
| 35 | -11835968 |
| 36 | 7620048 |
| 37 | 42944358 |
| 38 | 7464956 |
| 39 | -130615874 |
| 40 | -119900209 |