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 | 0 |
| 2 | 2 |
| 3 | -1 |
| 4 | 4 |
| 5 | -7 |
| 6 | 19 |
| 7 | -48 |
| 8 | 123 |
| 9 | -304 |
| 10 | 728 |
| 11 | -1694 |
| 12 | 3865 |
| 13 | -8735 |
| 14 | 19739 |
| 15 | -44875 |
| 16 | 102818 |
| 17 | -236939 |
| 18 | 546988 |
| 19 | -1260023 |
| 20 | 2888607 |
| 21 | -6584008 |
| 22 | 14927816 |
| 23 | -33714166 |
| 24 | 75976024 |
| 25 | -171095098 |
| 26 | 385405617 |
| 27 | -868708176 |
| 28 | 1959010348 |
| 29 | -4417777937 |
| 30 | 9957188242 |
| 31 | -22420045445 |