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A077485
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a(1) = 1, then smallest n-digit square which leaves a square at every step if most significant digit and least significant digit are deleted until a one-or two-digit digit square is obtained. a(2n) = 0 if no such square exists. a(2n+1) = 10^2n only if no nontrivial candidate exists.
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2
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1, 16, 144, 1369, 10816, 0, 1004004, 0, 100000000, 0, 10000400004, 0, 1000000000000, 0, 100000040000004, 0, 10000000000000000, 0, 1000000004000000004, 0, 100000000000000000000, 0, 10000000000400000000004
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OFFSET
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1,2
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LINKS
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FORMULA
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Beginning with term a(6) the following pattern applies: a(4k)=0; a(4k+1)=10^4k=(10^2k)^2; a(4k+2)=0; a(4k+3)=(10^(2k+1)+2)^2. - Ray Chandler, Aug 03 2003
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EXAMPLE
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a(3) = 144 as 144 and 4 are both squares.
a(4) = 1369 as 1369 and 36 are both squares.
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CROSSREFS
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KEYWORD
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base,nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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