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 | 0 |
| 4 | 1 |
| 5 | -1 |
| 6 | 1 |
| 7 | -4 |
| 8 | 11 |
| 9 | -18 |
| 10 | 18 |
| 11 | 0 |
| 12 | -60 |
| 13 | 189 |
| 14 | -360 |
| 15 | 453 |
| 16 | -373 |
| 17 | 294 |
| 18 | -652 |
| 19 | 1443 |
| 20 | -841 |
| 21 | -6127 |
| 22 | 27681 |
| 23 | -75150 |
| 24 | 172371 |
| 25 | -389662 |
| 26 | 867415 |
| 27 | -1630604 |
| 28 | 1826409 |
| 29 | 1738343 |
| 30 | -15855044 |
| 31 | 49812000 |
| 32 | -109702703 |
| 33 | 186277940 |
| 34 | -229343877 |
| 35 | 86783346 |
| 36 | 618570769 |
| 37 | -2635628596 |