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 | 0 |
| 2 | -3 |
| 3 | 3 |
| 4 | -6 |
| 5 | 9 |
| 6 | -15 |
| 7 | 21 |
| 8 | -33 |
| 9 | 48 |
| 10 | -75 |
| 11 | 111 |
| 12 | -168 |
| 13 | 252 |
| 14 | -381 |
| 15 | 570 |
| 16 | -858 |
| 17 | 1287 |
| 18 | -1932 |
| 19 | 2898 |
| 20 | -4350 |
| 21 | 6525 |
| 22 | -9789 |
| 23 | 14682 |
| 24 | -22026 |
| 25 | 33039 |
| 26 | -49560 |
| 27 | 74340 |
| 28 | -111513 |
| 29 | 167268 |
| 30 | -250905 |
| 31 | 376356 |
| 32 | -564537 |
| 33 | 846804 |
| 34 | -1270209 |
| 35 | 1905312 |
| 36 | -2857971 |
| 37 | 4286955 |
| 38 | -6430434 |
| 39 | 9645651 |