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) |
|---|---|
| 1 | -3 |
| 2 | 1 |
| 3 | -1 |
| 4 | 1 |
| 5 | -2 |
| 6 | 6 |
| 7 | -16 |
| 8 | 36 |
| 9 | -72 |
| 10 | 136 |
| 11 | -256 |
| 12 | 496 |
| 13 | -992 |
| 14 | 2016 |
| 15 | -4096 |
| 16 | 8256 |
| 17 | -16512 |
| 18 | 32896 |
| 19 | -65536 |
| 20 | 130816 |
| 21 | -261631 |
| 22 | 523754 |
| 23 | -1048323 |
| 24 | 2096152 |
| 25 | -4183701 |
| 26 | 8324850 |
| 27 | -16480855 |
| 28 | 32363020 |
| 29 | -62784775 |
| 30 | 119759850 |
| 31 | -223346545 |
| 32 | 404492000 |
| 33 | -705032195 |
| 34 | 1166803110 |