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 | 2 |
| 2 | -1 |
| 3 | 12 |
| 4 | -8 |
| 5 | 1 |
| 6 | 120 |
| 7 | -90 |
| 8 | 18 |
| 9 | -1 |
| 10 | 1680 |
| 11 | -1344 |
| 12 | 336 |
| 13 | -32 |
| 14 | 1 |
| 15 | 30240 |
| 16 | -25200 |
| 17 | 7200 |
| 18 | -900 |
| 19 | 50 |
| 20 | -1 |
| 21 | 665280 |
| 22 | -570240 |
| 23 | 178200 |
| 24 | -26400 |
| 25 | 1980 |
| 26 | -72 |
| 27 | 1 |
| 28 | 17297280 |
| 29 | -15135120 |
| 30 | 5045040 |
| 31 | -840840 |
| 32 | 76440 |
| 33 | -3822 |
| 34 | 98 |
| 35 | -1 |
| 36 | 518918400 |
| 37 | -461260800 |
| 38 | 161441280 |
| 39 | -29352960 |
| 40 | 3057600 |
| 41 | -188160 |
| 42 | 6720 |
| 43 | -128 |
| 44 | 1 |