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 | -1 |
| 2 | 0 |
| 3 | -8 |
| 4 | 19 |
| 5 | -106 |
| 6 | 406 |
| 7 | -1791 |
| 8 | 7470 |
| 9 | -31834 |
| 10 | 134541 |
| 11 | -570428 |
| 12 | 2415556 |
| 13 | -10233781 |
| 14 | 43348852 |
| 15 | -183632148 |
| 16 | 777872655 |
| 17 | -3295130518 |
| 18 | 13958382186 |
| 19 | -59128679555 |
| 20 | 250473067570 |
| 21 | -1061021002966 |
| 22 | 4494556993465 |
| 23 | -19039249115928 |
| 24 | 80651553232104 |
| 25 | -341645462408521 |
| 26 | 1447233402276936 |
| 27 | -6130579072469696 |
| 28 | 25969549690613035 |
| 29 | -110008777837417954 |
| 30 | 466004661036246046 |