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 | -8 |
| 2 | 35 |
| 3 | -161 |
| 4 | 854 |
| 5 | -5248 |
| 6 | 36966 |
| 7 | -294714 |
| 8 | 2628600 |
| 9 | -25963392 |
| 10 | 281529192 |
| 11 | -3326287848 |
| 12 | 42546905712 |
| 13 | -585889457328 |
| 14 | 8643254959008 |
| 15 | -136013600978784 |
| 16 | 2274436197944064 |
| 17 | -40278639752011008 |
| 18 | 753115809287568384 |
| 19 | -14826614346669090816 |
| 20 | 306574242780102220800 |