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Search: id:A130501
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| A130501 |
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a(1)=1. a(n) = number of earlier terms of the sequence which divide (the sum of positive integers which are <=n and missing from first (n-1) terms of sequence). |
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+0
2
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| 1, 1, 2, 2, 4, 4, 2, 2, 6, 7, 6, 6, 2, 2, 10, 8, 2, 3, 2, 2, 12, 15, 14, 11, 14, 15, 5, 17, 16, 11, 3, 2, 14, 16, 2, 3, 17, 15, 4, 2, 16, 17, 3, 2, 19, 4, 22, 19, 6, 2, 16, 24, 5, 2, 40, 33, 22, 21, 26, 17, 13, 26, 3, 6, 22, 17, 2, 2, 23, 7, 25, 2, 29, 3, 27, 8, 23, 26, 9, 20
(list; graph; listen)
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OFFSET
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1,3
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EXAMPLE
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The positive integers which are <= 9 and are missing from the first 8 terms of the sequence are 3,5,6,7,8,9. The sum of these integers is 38, so a(9) is the number of earlier terms which divide 38. Therefore a(9) = 6.
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MATHEMATICA
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a = {1}; Do[AppendTo[a, Length[Select[a, Mod[(Plus @@ Complement[Range[n], a]), # ] == 0 &]]], {n, 2, 80}]; a - Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Dec 26 2007
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CROSSREFS
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Cf. A130500.
Adjacent sequences: A130498 A130499 A130500 this_sequence A130502 A130503 A130504
Sequence in context: A097860 A098979 A071928 this_sequence A049116 A065176 A060267
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet (qq-quet(AT)mindspring.com), May 31 2007
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EXTENSIONS
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More terms from Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Dec 26 2007
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