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A243017
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Least number k > 0 such that k*n/(k+n) and k*n/(k-n) are integers or 0 if no such k exists.
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5
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0, 0, 6, 12, 0, 3, 0, 24, 18, 15, 0, 4, 0, 0, 10, 48, 0, 9, 0, 30, 28, 0, 0, 8, 0, 0, 54, 21, 0, 15, 0, 96, 66, 0, 210, 12, 0, 0, 78, 24, 0, 21, 0, 132, 30, 0, 0, 16, 0, 75, 102, 156, 0, 27, 66, 42, 114, 0, 0, 12, 0, 0, 84, 192, 0, 33, 0, 204, 138, 105, 0, 24, 0, 0, 50, 228
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OFFSET
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1,3
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LINKS
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EXAMPLE
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3*6/(6+3) = 2 and 3*6/(6-3) = 9 are both integers. Thus a(3) = 6.
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PROG
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(PARI) a(n)=for(k=1, n*(n+1), if(k!=n, if((k*n)%(k+n)==0&&(k*n)%(k-n)==0, return(k))))
n=1; while(n<100, print1(a(n), ", "); n+=1)
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CROSSREFS
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KEYWORD
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AUTHOR
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STATUS
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approved
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