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) |
|---|---|
| 1 | 1 |
| 2 | -1 |
| 3 | 2 |
| 4 | -3 |
| 5 | 7 |
| 6 | -12 |
| 7 | 30 |
| 8 | -55 |
| 9 | 143 |
| 10 | -273 |
| 11 | 728 |
| 12 | -1428 |
| 13 | 3876 |
| 14 | -7752 |
| 15 | 21318 |
| 16 | -43263 |
| 17 | 120175 |
| 18 | -246675 |
| 19 | 690690 |
| 20 | -1430715 |
| 21 | 4032015 |
| 22 | -8414640 |
| 23 | 23841480 |
| 24 | -50067108 |
| 25 | 142498692 |
| 26 | -300830572 |
| 27 | 859515920 |
| 28 | -1822766520 |
| 29 | 5225264024 |
| 30 | -11124755664 |
| 31 | 31983672534 |
| 32 | -68328754959 |