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 | -5 |
| 3 | -13 |
| 4 | 115 |
| 5 | 2099 |
| 6 | 11395 |
| 7 | -177373 |
| 8 | -5116685 |
| 9 | -40481581 |
| 10 | 948973795 |
| 11 | 36701972867 |
| 12 | 375364322515 |
| 13 | -12090607539661 |
| 14 | -580544884927805 |
| 15 | -7188739235243293 |
| 16 | 301374306966657715 |
| 17 | 17150539711123411859 |
| 18 | 246564346727945106595 |
| 19 | -12988846468460187345853 |