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 | 3 |
| 2 | 9 |
| 3 | 18 |
| 4 | -27 |
| 5 | -552 |
| 6 | -3051 |
| 7 | -3504 |
| 8 | 102825 |
| 9 | 1043712 |
| 10 | 3192129 |
| 11 | -41548416 |
| 12 | -653192883 |
| 13 | -3033406464 |
| 14 | 31367500173 |
| 15 | 670266381312 |
| 16 | 3916411302609 |
| 17 | -40460110970880 |
| 18 | -1038593550985479 |
| 19 | -6810646726410240 |
| 20 | 82445831323038261 |
| 21 | 2280185182260854784 |
| 22 | 15300402721484153733 |