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) |
|---|---|
| 2 | 1 |
| 3 | -1 |
| 4 | 0 |
| 5 | 1 |
| 6 | 0 |
| 7 | -3 |
| 8 | -1 |
| 9 | 14 |
| 10 | 20 |
| 11 | -77 |
| 12 | -308 |
| 13 | 147 |
| 14 | 3965 |
| 15 | 12527 |
| 16 | -26255 |
| 17 | -446923 |
| 18 | -1127033 |
| 19 | 9020388 |
| 20 | 71170748 |
| 21 | 57286010 |
| 22 | -2168151928 |
| 23 | -17700260071 |
| 24 | -11899834419 |
| 25 | 993097077555 |
| 26 | 7077421523510 |
| 27 | -12873010724109 |