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 | -2 |
| 3 | -9 |
| 4 | 267 |
| 5 | -2180 |
| 6 | -50533 |
| 7 | 1966797 |
| 8 | 8638718 |
| 9 | -2540956509 |
| 10 | 27172288399 |
| 11 | 5592543175252 |
| 12 | -168392610536153 |
| 13 | -20819319685262839 |
| 14 | 1122009166836993406 |
| 15 | 127595724180314195839 |
| 16 | -9985347479130060737373 |
| 17 | -1244077225312583088164916 |
| 18 | 120225865637787689310572899 |
| 19 | 18462990063073814590636032245 |