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A175874
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a(n) = least number such that sigma(a(n)+n)=n*sigma(a(n)).
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2
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OFFSET
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1,1
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COMMENTS
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Is n = 2 the only solution for sigma(n+4)=4*sigma(n)? - Zak Seidov, Jul 07 2013
A further solution to sigma(n+4)=4*sigma(n), and the terms a(5) and a(6), if they exist, they are all larger than 3*10^12. - Giovanni Resta, Jun 06 2016
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LINKS
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EXAMPLE
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sigma(14+1)/sigma(14)=24/24=1, sigma(118+2)/sigma(118)=360/180=2,
sigma(3+3)/sigma(3)=12/4=3, sigma(4+4)/sigma(2)=12/3=4.
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CROSSREFS
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KEYWORD
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more,nonn
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AUTHOR
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STATUS
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approved
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