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 | 0 |
| 1 | 1 |
| 2 | -3 |
| 3 | 10 |
| 4 | -38 |
| 5 | 158 |
| 6 | -698 |
| 7 | 3218 |
| 8 | -15310 |
| 9 | 74614 |
| 10 | -370610 |
| 11 | 1869338 |
| 12 | -9549174 |
| 13 | 49302030 |
| 14 | -256859754 |
| 15 | 1348695330 |
| 16 | -7129819038 |
| 17 | 37916710374 |
| 18 | -202708895330 |
| 19 | 1088819681834 |
| 20 | -5873129780422 |
| 21 | 31800514324606 |
| 22 | -172780691083034 |
| 23 | 941714095635890 |
| 24 | -5147414826440558 |
| 25 | 28210011946820438 |