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Search: id:A130109
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| A130109 |
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Rearrangement of natural numbers such that each two terms sum up to a perfect square. |
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+0
4
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| 1, 3, 2, 7, 4, 5, 6, 10, 8, 17, 9, 16, 11, 14, 12, 13, 15, 21, 18, 31, 19, 30, 20, 29, 22, 27, 23, 26, 24, 25, 28, 36, 32, 49, 33, 48, 34, 47, 35, 46, 37, 44, 38, 43, 39, 42, 40, 41, 45, 55, 50, 71, 51, 70, 52, 69, 53, 68, 54, 67, 56, 65, 57, 64, 58, 63, 59, 62, 60, 61, 66, 78
(list; graph; listen)
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OFFSET
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1,2
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EXAMPLE
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1+3=4, 2+7=9, 4+5=9, 6+10=16, 8+17=25.
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MATHEMATICA
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s={}; ra=Range[2000]; Do[su=ra[[1]]; c=2; While[ !IntegerQ[Sqrt[su+ra[[c]]]], c++ ]; rac=ra[[c]]; s=Join[s, {ra[[1]], rac}]; ra=Complement[ra, {ra[[1]], rac}], {133}]; s
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CROSSREFS
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Cf. A130108, A130110, A130111.
Sequence in context: A129187 A166532 A135542 this_sequence A153151 A153154 A154438
Adjacent sequences: A130106 A130107 A130108 this_sequence A130110 A130111 A130112
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KEYWORD
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nonn
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AUTHOR
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Zak Seidov (zakseidov(AT)yahoo.com), May 08 2007
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