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 | -1 |
| 2 | -4 |
| 3 | -25 |
| 4 | -252 |
| 5 | -3545 |
| 6 | -63806 |
| 7 | -1397781 |
| 8 | -36069272 |
| 9 | -1071165745 |
| 10 | -35977484250 |
| 11 | -1348257912221 |
| 12 | -55766033179220 |
| 13 | -2523251585908521 |
| 14 | -123972318738063446 |
| 15 | -6572554273909419685 |
| 16 | -373979858167243433136 |
| 17 | -22731929051273411113313 |
| 18 | -1470009560015441800798514 |