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 | -2 |
| 2 | 1 |
| 3 | -1 |
| 4 | -9 |
| 5 | -59 |
| 6 | -474 |
| 7 | -4560 |
| 8 | -50364 |
| 9 | -625385 |
| 10 | -8622658 |
| 11 | -130751886 |
| 12 | -2163331779 |
| 13 | -38793751015 |
| 14 | -749691306018 |
| 15 | -15535914341831 |
| 16 | -343749787006758 |
| 17 | -8089725377931547 |
| 18 | -201801866906374263 |
| 19 | -5319643146604299835 |
| 20 | -147774950436327236681 |