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 | 0 |
| 2 | 27 |
| 3 | 539 |
| 4 | 9800 |
| 5 | 176175 |
| 6 | 3162159 |
| 7 | 56744792 |
| 8 | 1018249595 |
| 9 | 18271762299 |
| 10 | 327873509424 |
| 11 | 5883451505855 |
| 12 | 105574253853887 |
| 13 | 1894453118539344 |
| 14 | 33994581881622075 |
| 15 | 610008020755286075 |
| 16 | 10946149791725643704 |
| 17 | 196420688230338021807 |
| 18 | 3524626238354441796015 |
| 19 | 63246851602149831726824 |