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 | 0 |
| 2 | 1 |
| 3 | 0 |
| 4 | -2 |
| 5 | 1 |
| 6 | 0 |
| 7 | 12 |
| 8 | -8 |
| 9 | 1 |
| 10 | 0 |
| 11 | -144 |
| 12 | 108 |
| 13 | -20 |
| 14 | 1 |
| 15 | 0 |
| 16 | 2880 |
| 17 | -2304 |
| 18 | 508 |
| 19 | -40 |
| 20 | 1 |
| 21 | 0 |
| 22 | -86400 |
| 23 | 72000 |
| 24 | -17544 |
| 25 | 1708 |
| 26 | -70 |
| 27 | 1 |
| 28 | 0 |
| 29 | 3628800 |
| 30 | -3110400 |
| 31 | 808848 |
| 32 | -89280 |
| 33 | 4648 |
| 34 | -112 |
| 35 | 1 |
| 36 | 0 |
| 37 | -203212800 |
| 38 | 177811200 |
| 39 | -48405888 |
| 40 | 5808528 |
| 41 | -349568 |
| 42 | 10920 |
| 43 | -168 |
| 44 | 1 |
| 45 | 0 |
| 46 | 14631321600 |
| 47 | -13005619200 |
| 48 | 3663035136 |
| 49 | -466619904 |
| 50 | 30977424 |
| 51 | -1135808 |
| 52 | 23016 |
| 53 | -240 |
| 54 | 1 |