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A051611
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Numbers that are not the sum of 2 nonzero triangular numbers.
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6
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1, 3, 5, 8, 10, 14, 15, 17, 19, 23, 26, 28, 32, 33, 35, 40, 41, 44, 45, 47, 50, 52, 53, 54, 59, 62, 63, 68, 71, 74, 75, 77, 78, 80, 82, 85, 86, 89, 95, 96, 98, 103, 104, 105, 107, 109, 113, 116, 117, 118, 122, 124, 125, 128, 129, 131, 134, 138, 140, 143, 145, 147
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,2
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LINKS
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T. D. Noe, Table of n, a(n) for n=1..1000
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MATHEMATICA
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notSumQ[n_] := Reduce[ 0 < x <= y && n == x*(x + 1)/2 + y*(y + 1)/2, {x, y}, Integers] === False; Select[ Range[150], notSumQ] (* Jean-François Alcover, Jun 27 2012 *)
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CROSSREFS
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Integers not in the sequence A051533. Cf. A002097, A000217, A007294, A051611, A053603.
Sequence in context: A072150 A091309 A027922 * A005004 A006218 A062839
Adjacent sequences: A051608 A051609 A051610 * A051612 A051613 A051614
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KEYWORD
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easy,nonn,nice
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AUTHOR
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Klaus Strassburger (strass(AT)ddfi.uni-duesseldorf.de)
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STATUS
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approved
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