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A108903
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Numbers such that the outer 2 digits are 9 and the inner digits are 5.
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1
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959, 9559, 95559, 955559, 9555559, 95555559, 955555559, 9555555559, 95555555559, 955555555559, 9555555555559, 95555555555559, 955555555555559, 9555555555555559, 95555555555555559, 955555555555555559
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OFFSET
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1,1
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COMMENTS
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These numbers are all composite. They are divisible among other numbers by 3,7,11,13 depending on the form 6k+r, 0 < r < 6. See the link for a proof.
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LINKS
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FORMULA
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S(x)=9*10^(x+1)+ 9 + 50*(10^x-1)/9.
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PROG
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(PARI) g(n, r, m) = epeat rrr.. surrounded by 2 m's { for(x=1, n, y=m*10^(x+1)+m+r*10*(10^x-1)/9; print(x", ") ) }
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CROSSREFS
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KEYWORD
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easy,nonn,base
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AUTHOR
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STATUS
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approved
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