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Old 2020-02-25, 09:53   #1
enzocreti
 
Mar 2018

17·31 Posts
Default 210=2*3*5*7

Is 210 the only primorial that can be written as n(n-1) with n an integer?


210=15*14
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Old 2020-02-25, 11:38   #2
axn
 
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Jun 2003

12ED16 Posts
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No.

2=1*2
6=2*3
30=2*3*5=5*6

510510=2*3*5*7*11*13*17=714*715

Last fiddled with by axn on 2020-02-25 at 11:40
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