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Search: id:A069000
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| A069000 |
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n * digit complement of n is a square. (Leading 0's are ignored.) |
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+0
1
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| 9, 99, 972, 999, 9900, 9999, 39204, 60975, 99999, 168399, 307692, 467775, 532224, 692307, 831600, 972972, 999999, 9946224, 9999999
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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The digit complement of a digit d is 9 - d, e.g. 8 and 3 have complements 1, 6, respectively. The digit complement of a number n is the number formed by replacing each digit of n by its complement, e.g. 83 has complement 16.
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EXAMPLE
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972972 has complement 27027 (the leading 0 is ignored). 972972 * 27027 = 162162^2, so 972972 is a term of the sequence.
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MATHEMATICA
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j[n_] := 9 - n; Do[If[IntegerQ[Sqrt[n*FromDigits[Map[j, IntegerDigits[n]]]]], Print[n]], {n, 1, 10^6}]
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CROSSREFS
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Sequence in context: A160946 A100681 A043044 this_sequence A101564 A070843 A108908
Adjacent sequences: A068997 A068998 A068999 this_sequence A069001 A069002 A069003
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KEYWORD
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base,nonn
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AUTHOR
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Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Mar 20 2002
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EXTENSIONS
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More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), Apr 08 2002
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