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 | -2 |
| 4 | 5 |
| 5 | 6 |
| 6 | -30 |
| 7 | -13 |
| 8 | 189 |
| 9 | -56 |
| 10 | -1188 |
| 11 | 1266 |
| 12 | 7194 |
| 13 | -14377 |
| 14 | -40183 |
| 15 | 135278 |
| 16 | 188773 |
| 17 | -1151800 |
| 18 | -503880 |
| 19 | 9109076 |
| 20 | -3419924 |
| 21 | -67220176 |
| 22 | 80390824 |
| 23 | 458183898 |
| 24 | -998680470 |
| 25 | -2794491329 |
| 26 | 10156144385 |
| 27 | 13919066170 |
| 28 | -92250872385 |
| 29 | -36047778330 |
| 30 | 769826420850 |
| 31 | -339940775445 |