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A247264
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Smallest positive number not divisible by 10 whose square remains a square when prefixed with 10^n.
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4
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OFFSET
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0,1
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LINKS
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EXAMPLE
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a(0) = 15 since 15^2 = 225 and 1225 is square and 15 is the smallest number not ending in 0 with this property. a(3) = 375 since 375^2 = 140625 and 1000140625 is square and 375 is the smallest number not ending in 0 with this property.
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PROG
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(PARI)
a(n)=k=1; while(k^2%100==0||!issquare(10^(#Str(k^2)+n)+k^2), k++); k^2
n=0; while(n<10, print1(a(n), ", "); n++) \\ Derek Orr, Sep 13 2014
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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