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 | 1 |
| 4 | -4 |
| 5 | 3 |
| 6 | 1 |
| 7 | -13 |
| 8 | 33 |
| 9 | -21 |
| 10 | 1 |
| 11 | -40 |
| 12 | 270 |
| 13 | -546 |
| 14 | 315 |
| 15 | 1 |
| 16 | -121 |
| 17 | 2010 |
| 18 | -10080 |
| 19 | 17955 |
| 20 | -9765 |
| 21 | 1 |
| 22 | -364 |
| 23 | 14433 |
| 24 | -165270 |
| 25 | 707805 |
| 26 | -1171800 |
| 27 | 615195 |
| 28 | 1 |
| 29 | -1093 |
| 30 | 102123 |
| 31 | -2580081 |
| 32 | 24421005 |
| 33 | -95765355 |
| 34 | 151953165 |
| 35 | -78129765 |
| 36 | 1 |
| 37 | -3280 |
| 38 | 718140 |
| 39 | -39416076 |
| 40 | 795752370 |
| 41 | -6790268520 |
| 42 | 25331269320 |
| 43 | -39221142030 |
| 44 | 19923090075 |