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 | 0 |
| 2 | 0 |
| 3 | -1 |
| 4 | 0 |
| 5 | -1 |
| 6 | -2 |
| 7 | 0 |
| 8 | -2 |
| 9 | -6 |
| 10 | -3 |
| 11 | 0 |
| 12 | -6 |
| 13 | -22 |
| 14 | -18 |
| 15 | -4 |
| 16 | 0 |
| 17 | -24 |
| 18 | -100 |
| 19 | -105 |
| 20 | -40 |
| 21 | -5 |
| 22 | 0 |
| 23 | -120 |
| 24 | -548 |
| 25 | -675 |
| 26 | -340 |
| 27 | -75 |
| 28 | -6 |
| 29 | 0 |
| 30 | -720 |
| 31 | -3528 |
| 32 | -4872 |
| 33 | -2940 |
| 34 | -875 |
| 35 | -126 |
| 36 | -7 |
| 37 | 0 |
| 38 | -5040 |
| 39 | -26136 |
| 40 | -39396 |
| 41 | -27076 |
| 42 | -9800 |
| 43 | -1932 |
| 44 | -196 |
| 45 | -8 |
| 46 | 0 |
| 47 | -40320 |
| 48 | -219168 |
| 49 | -354372 |
| 50 | -269136 |
| 51 | -112245 |
| 52 | -27216 |
| 53 | -3822 |
| 54 | -288 |
| 55 | -9 |
| 56 | 0 |
| 57 | -362880 |