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 | -13 |
| 3 | 10 |
| 4 | 1813 |
| 5 | -470 |
| 6 | -161653 |
| 7 | 42070 |
| 8 | 13387093 |
| 9 | -6278606 |
| 10 | -5451121865 |
| 11 | 1420802350 |
| 12 | 61102622050543 |
| 13 | -455069110262 |
| 14 | -50154461699251 |
| 15 | 196108344641350 |
| 16 | 2099332299244083701 |
| 17 | -109448263403739038 |
| 18 | -2062360862658074555671 |
| 19 | 76800655398762907870 |