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 | -4 |
| 6 | 3 |
| 7 | -1 |
| 8 | 17 |
| 9 | -16 |
| 10 | 21 |
| 11 | -57 |
| 12 | 67 |
| 13 | -130 |
| 14 | 305 |
| 15 | -536 |
| 16 | 995 |
| 17 | -1726 |
| 18 | 2652 |
| 19 | -4286 |
| 20 | 7320 |
| 21 | -13043 |
| 22 | 24458 |
| 23 | -45405 |
| 24 | 81415 |
| 25 | -141724 |
| 26 | 239755 |
| 27 | -400603 |
| 28 | 676872 |
| 29 | -1171076 |
| 30 | 2072334 |
| 31 | -3695550 |
| 32 | 6519951 |
| 33 | -11279015 |
| 34 | 19188230 |
| 35 | -32462795 |
| 36 | 55334284 |
| 37 | -95718737 |
| 38 | 167673672 |
| 39 | -294894076 |