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 | 1 |
| 2 | -1 |
| 3 | -2 |
| 4 | 3 |
| 5 | 2 |
| 6 | -1 |
| 7 | -5 |
| 8 | 25 |
| 9 | -20 |
| 10 | -16 |
| 11 | -7 |
| 12 | 23 |
| 13 | -39 |
| 14 | 25 |
| 15 | 309 |
| 16 | 455 |
| 17 | 901 |
| 18 | -2168 |
| 19 | 920 |
| 20 | 1047 |
| 21 | 2302 |
| 22 | -1536 |
| 23 | 3272 |
| 24 | 161162 |
| 25 | -289493 |
| 26 | -529263 |
| 27 | 1418949 |
| 28 | -1562590 |
| 29 | -579999 |
| 30 | 15145 |
| 31 | 5844471 |
| 32 | 5244416 |
| 33 | -65749104 |
| 34 | 176617384 |
| 35 | 2077411081 |
| 36 | 7381004327 |
| 37 | 10211507191 |
| 38 | -10333531933 |
| 39 | 7086785521 |
| 40 | 8502336136 |