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) |
|---|---|
| 1 | -1 |
| 2 | 3 |
| 3 | -11 |
| 4 | 63 |
| 5 | -571 |
| 6 | 7623 |
| 7 | -140531 |
| 8 | 3417183 |
| 9 | -105946891 |
| 10 | 4079170743 |
| 11 | -190947551651 |
| 12 | 10679561580303 |
| 13 | -703342782666811 |
| 14 | 53875223570677863 |
| 15 | -4749070236390684371 |
| 16 | 477331966210918815423 |
| 17 | -54264228263241408276331 |
| 18 | 6927625954707653092264983 |
| 19 | -986892857756676619338994691 |