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 | 1 |
| 3 | 5 |
| 4 | 9 |
| 5 | 129 |
| 6 | 57 |
| 7 | 9141 |
| 8 | -36879 |
| 9 | 1430049 |
| 10 | -15439407 |
| 11 | 418019205 |
| 12 | -7404957255 |
| 13 | 196896257505 |
| 14 | -4656470025015 |
| 15 | 134136890777205 |
| 16 | -3845524501226655 |
| 17 | 123250625100419265 |
| 18 | -4085349586734306015 |
| 19 | 145973136800663973765 |