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 | 6 |
| 2 | -30 |
| 3 | -246 |
| 4 | 834 |
| 5 | 9690 |
| 6 | -20334 |
| 7 | -369174 |
| 8 | 362850 |
| 9 | 13653114 |
| 10 | 590514 |
| 11 | -490921590 |
| 12 | -512180094 |
| 13 | 17160997146 |
| 14 | 35599480530 |
| 15 | -582196416726 |
| 16 | -1863777715806 |
| 17 | 19095293286330 |
| 18 | 86191291055346 |
| 19 | -601239267252534 |
| 20 | -3704125745244990 |
| 21 | 17940487875846234 |