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 | 1 |
| 4 | -3 |
| 5 | 2 |
| 6 | 1 |
| 7 | -7 |
| 8 | 12 |
| 9 | -6 |
| 10 | 1 |
| 11 | -15 |
| 12 | 50 |
| 13 | -60 |
| 14 | 24 |
| 15 | 1 |
| 16 | -31 |
| 17 | 180 |
| 18 | -390 |
| 19 | 360 |
| 20 | -120 |
| 21 | 1 |
| 22 | -63 |
| 23 | 602 |
| 24 | -2100 |
| 25 | 3360 |
| 26 | -2520 |
| 27 | 720 |
| 28 | 1 |
| 29 | -127 |
| 30 | 1932 |
| 31 | -10206 |
| 32 | 25200 |
| 33 | -31920 |
| 34 | 20160 |
| 35 | -5040 |
| 36 | 1 |
| 37 | -255 |
| 38 | 6050 |
| 39 | -46620 |
| 40 | 166824 |
| 41 | -317520 |
| 42 | 332640 |
| 43 | -181440 |
| 44 | 40320 |
| 45 | 1 |
| 46 | -511 |
| 47 | 18660 |