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 | 4 |
| 3 | 15 |
| 4 | -14 |
| 5 | 185 |
| 6 | -454 |
| 7 | 2107 |
| 8 | -6194 |
| 9 | 22689 |
| 10 | -70058 |
| 11 | 234971 |
| 12 | -734304 |
| 13 | 2368379 |
| 14 | -7404318 |
| 15 | 23417955 |
| 16 | -72988938 |
| 17 | 228324569 |
| 18 | -708982738 |
| 19 | 2202742447 |
| 20 | -6815736144 |
| 21 | 21077285943 |
| 22 | -65016664062 |
| 23 | 200371842727 |
| 24 | -616463969324 |
| 25 | 1894794918275 |
| 26 | -5816606133674 |
| 27 | 17839764136377 |