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 | 0 |
| 3 | 0 |
| 4 | 1 |
| 5 | -1 |
| 6 | 0 |
| 7 | 6 |
| 8 | -19 |
| 9 | 29 |
| 10 | 48 |
| 11 | -524 |
| 12 | 2057 |
| 13 | -3901 |
| 14 | -9632 |
| 15 | 129034 |
| 16 | -664363 |
| 17 | 1837905 |
| 18 | 2388688 |
| 19 | -67004696 |
| 20 | 478198545 |
| 21 | -1994889945 |
| 22 | 1669470784 |
| 23 | 56929813934 |
| 24 | -615188040195 |
| 25 | 3794477505573 |
| 26 | -12028579019536 |
| 27 | -50780206473220 |