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 | -2 |
| 3 | -5 |
| 4 | 24 |
| 5 | 81 |
| 6 | -439 |
| 7 | -1590 |
| 8 | 9144 |
| 9 | 34451 |
| 10 | -206641 |
| 11 | -799196 |
| 12 | 4936378 |
| 13 | 19442800 |
| 14 | -122613798 |
| 15 | -489411508 |
| 16 | 3134773097 |
| 17 | 12640278932 |
| 18 | -81948641010 |
| 19 | -333099985517 |
| 20 | 2180523864984 |
| 21 | 8920922434686 |
| 22 | -58861487584914 |
| 23 | -242105281357185 |
| 24 | 1608002839956522 |
| 25 | 6643707274089977 |
| 26 | -44372373955131024 |