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 | 2 |
| 5 | 1 |
| 6 | 4 |
| 7 | 0 |
| 8 | 8 |
| 9 | -3 |
| 10 | 16 |
| 11 | -12 |
| 12 | 36 |
| 13 | -40 |
| 14 | 88 |
| 15 | -117 |
| 16 | 220 |
| 17 | -321 |
| 18 | 560 |
| 19 | -860 |
| 20 | 1447 |
| 21 | -2284 |
| 22 | 3772 |
| 23 | -6032 |
| 24 | 9861 |
| 25 | -15864 |
| 26 | 25798 |
| 27 | -41627 |
| 28 | 67527 |
| 29 | -109132 |
| 30 | 176826 |
| 31 | -285985 |
| 32 | 463089 |
| 33 | -749189 |
| 34 | 1212722 |
| 35 | -1962181 |
| 36 | 3175635 |
| 37 | -5138421 |
| 38 | 8315361 |
| 39 | -13455103 |
| 40 | 21772865 |