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 | -2 |
| 3 | 5 |
| 4 | -15 |
| 5 | 52 |
| 6 | -200 |
| 7 | 827 |
| 8 | -3596 |
| 9 | 16191 |
| 10 | -74702 |
| 11 | 350794 |
| 12 | -1669439 |
| 13 | 8029728 |
| 14 | -38963552 |
| 15 | 190499461 |
| 16 | -937550897 |
| 17 | 4641253152 |
| 18 | -23096403422 |
| 19 | 115475977145 |
| 20 | -579799302750 |
| 21 | 2922325238788 |
| 22 | -14780595276064 |
| 23 | 74995317703482 |
| 24 | -381625745964018 |
| 25 | 1947147485751919 |