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 | 2 |
| 2 | 9 |
| 3 | 30 |
| 4 | 60 |
| 5 | 122 |
| 6 | -878 |
| 7 | 11429 |
| 8 | 35241 |
| 9 | -177141 |
| 10 | 709582 |
| 11 | -3123032 |
| 12 | -1157723745 |
| 13 | 3237738813 |
| 14 | -16178936725 |
| 15 | 33395053634 |
| 16 | -71863018424 |
| 17 | -153349368674 |
| 18 | -386763022623 |
| 19 | -8021033029400 |
| 20 | 16314606875900 |
| 21 | 52522689388692 |