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 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | -2 |
| 4 | 5 |
| 5 | -11 |
| 6 | 23 |
| 7 | -48 |
| 8 | 102 |
| 9 | -220 |
| 10 | 476 |
| 11 | -1024 |
| 12 | 2184 |
| 13 | -4624 |
| 14 | 9744 |
| 15 | -20480 |
| 16 | 42976 |
| 17 | -90048 |
| 18 | 188352 |
| 19 | -393216 |
| 20 | 819328 |
| 21 | -1704192 |
| 22 | 3539200 |
| 23 | -7340032 |
| 24 | 15203840 |
| 25 | -31456256 |
| 26 | 65010688 |
| 27 | -134217728 |
| 28 | 276826112 |
| 29 | -570429440 |
| 30 | 1174409216 |