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 | -1 |
| 3 | -3 |
| 4 | -5 |
| 5 | 441 |
| 6 | 25911 |
| 7 | 1384757 |
| 8 | 74436531 |
| 9 | 3175224945 |
| 10 | -135369432209 |
| 11 | -89771310955155 |
| 12 | -25527579751884693 |
| 13 | -6567045994040209879 |
| 14 | -1678101422880410465625 |
| 15 | -427686430807976068014939 |
| 16 | -102728760825086263958009309 |
| 17 | -18156608776369804213731821343 |
| 18 | 2585946334251026101959272934111 |