σ(a) = σ(b) = a + b + 1

 
 

To find pairs   (a, b),   a < b   such that   \sigma(a) = \sigma(b) = a + b + 1

 
for example,
 

\sigma(48) \; = \; \sigma(75) \; = \; 48 \; + \; 75 \; + \; 1 \; = \; 124

\sigma(140) \; = \; \sigma(195) \; = \; 140 \; + \; 195 \; + \; 1 \; = \; 336

\sigma(1575) \; = \; \sigma(1648) \; = \; 1575 \; + \; 1648 \; + \; 1 \; = \; 3224

\sigma(1050) \; = \; \sigma(1925) \; = \; 1050 \; + \; 1925 \; + \; 1 \; = \; 2976

\sigma(2024) \; = \; \sigma(2295) \; = \; 2024 \; + \; 2295 \; + \; 1 \; = \; 4320

 

Find other pairs
 
 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

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About benvitalis

math grad - Interest: Number theory
This entry was posted in Number Puzzles and tagged . Bookmark the permalink.

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