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 | -3 |
| 5 | 1 |
| 6 | 6 |
| 7 | -12 |
| 8 | 7 |
| 9 | -1 |
| 10 | 24 |
| 11 | -60 |
| 12 | 50 |
| 13 | -15 |
| 14 | 1 |
| 15 | 120 |
| 16 | -360 |
| 17 | 390 |
| 18 | -180 |
| 19 | 31 |
| 20 | -1 |
| 21 | 720 |
| 22 | -2520 |
| 23 | 3360 |
| 24 | -2100 |
| 25 | 602 |
| 26 | -63 |
| 27 | 1 |
| 28 | 5040 |
| 29 | -20160 |
| 30 | 31920 |
| 31 | -25200 |
| 32 | 10206 |
| 33 | -1932 |
| 34 | 127 |
| 35 | -1 |
| 36 | 40320 |
| 37 | -181440 |
| 38 | 332640 |
| 39 | -317520 |
| 40 | 166824 |
| 41 | -46620 |
| 42 | 6050 |
| 43 | -255 |
| 44 | 1 |
| 45 | 362880 |
| 46 | -1814400 |
| 47 | 3780000 |
| 48 | -4233600 |
| 49 | 2739240 |
| 50 | -1020600 |
| 51 | 204630 |
| 52 | -18660 |
| 53 | 511 |
| 54 | -1 |