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 | -12 |
| 5 | 33 |
| 6 | -78 |
| 7 | 261 |
| 8 | -360 |
| 9 | 3681 |
| 10 | 13446 |
| 11 | 193509 |
| 12 | 1951452 |
| 13 | 23948865 |
| 14 | 309740922 |
| 15 | 4341155877 |
| 16 | 65102989248 |
| 17 | 1041690874689 |
| 18 | 17708615729550 |
| 19 | 318755470552389 |
| 20 | 6056352778233924 |
| 21 | 121127059051462881 |
| 22 | 2543668229620367298 |