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Can there exist two distinct integers $x$ and $y$ such that $x,y$ have the same prime factors, $x+1,y+1$ have the same prime factors, and $x+2,y+2$ also have the same prime factors?
For just $x,y$ and $x+1,y+1$ one can take \[x=2(2^r-1)\] and \[y = x(x+2).\] Erdős also asked whether there are any other examples. Matthew Bolan has observed that $x=75$ and $y=1215$ is another example, since \[75 = 3\cdot 5^2 \textrm{ and }1215 = 3^5\cdot 5\] while \[76 = 2^2\cdot 19\textrm{ and }1216 = 2^6\cdot 19.\] No other examples are known. This sequence is listed as A343101 at the OEIS.

See also [677].

Additional thanks to: Matthew Bolan