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 | -3 |
| 2 | 7 |
| 3 | -18 |
| 4 | 47 |
| 5 | -123 |
| 6 | 322 |
| 7 | -843 |
| 8 | 2207 |
| 9 | -5778 |
| 10 | 15127 |
| 11 | -39603 |
| 12 | 103682 |
| 13 | -271443 |
| 14 | 710647 |
| 15 | -1860498 |
| 16 | 4870847 |
| 17 | -12752043 |
| 18 | 33385282 |
| 19 | -87403803 |
| 20 | 228826127 |
| 21 | -599074578 |
| 22 | 1568397607 |
| 23 | -4106118243 |
| 24 | 10749957122 |
| 25 | -28143753123 |
| 26 | 73681302247 |
| 27 | -192900153618 |
| 28 | 505019158607 |