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 | 1 |
| 2 | -1 |
| 3 | 3 |
| 4 | -2 |
| 5 | -15 |
| 6 | 20 |
| 7 | -6 |
| 8 | 105 |
| 9 | -210 |
| 10 | 40 |
| 11 | 90 |
| 12 | -24 |
| 13 | -945 |
| 14 | 2520 |
| 15 | -1120 |
| 16 | -1260 |
| 17 | 420 |
| 18 | 504 |
| 19 | -120 |
| 20 | 10395 |
| 21 | -34650 |
| 22 | 25200 |
| 23 | 18900 |
| 24 | -2240 |
| 25 | -15120 |
| 26 | -9072 |
| 27 | 1260 |
| 28 | 2688 |
| 29 | 3360 |
| 30 | -720 |
| 31 | -135135 |
| 32 | 540540 |
| 33 | -554400 |
| 34 | -311850 |
| 35 | 123200 |
| 36 | 415800 |
| 37 | 166320 |
| 38 | -50400 |
| 39 | -56700 |
| 40 | -120960 |
| 41 | -75600 |
| 42 | 18144 |
| 43 | 20160 |
| 44 | 25920 |
| 45 | -5040 |