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 | -1 |
| 3 | -11 |
| 4 | -95 |
| 5 | -1321 |
| 6 | -22561 |
| 7 | -474851 |
| 8 | -11785535 |
| 9 | -337650001 |
| 10 | -10962505921 |
| 11 | -397804232891 |
| 12 | -15954963362975 |
| 13 | -700861670953081 |
| 14 | -33464274136282081 |
| 15 | -1725656338796874131 |
| 16 | -95578727098089100415 |
| 17 | -5658893822397686566561 |
| 18 | -356659432609686011399041 |
| 19 | -23841281202421071709150571 |