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 | -30 |
| 2 | -3150 |
| 3 | -472500 |
| 4 | -81506250 |
| 5 | -15160162500 |
| 6 | -2956231687500 |
| 7 | -595469525625000 |
| 8 | -122815589660156250 |
| 9 | -25791273828632812500 |
| 10 | -5493541325498789062500 |
| 11 | -1183608449221102734375000 |
| 12 | -257434837705589844726562500 |
| 13 | -56437637496994696728515625000 |