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Search: id:A067131
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| A067131 |
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Number of elements in the largest set of divisors of n which are in arithmetic progression. |
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+0
2
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| 1, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 4, 2, 2, 3, 2, 2, 3, 2, 2, 2, 2, 2, 4, 2, 2, 2, 3, 2, 3, 2, 2, 2, 2, 2, 4, 2, 2, 2, 3, 2, 3, 2, 2, 3, 2, 2, 4, 2, 2, 2, 2, 2, 3, 2, 3, 2, 2, 2, 6, 2, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 4, 2, 2, 3, 2, 2, 3, 2, 3, 2, 2, 2, 4, 2, 2, 2, 2, 2, 3, 3, 2, 2, 2, 2, 4, 2, 2, 2, 2, 2, 3, 2
(list; graph; listen)
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OFFSET
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1,2
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EXAMPLE
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a(12) = 4 as the divisors of 12 are {1,2,3,4,6,12} and the maximal subset in arithmetic progression is {1,2,3,4}. a(15) = 3; the maximal set is {1,3,5}.
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MATHEMATICA
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lap[s_] := Module[{}, l=Length[s]; If[l<2, Return[l]]; val=2; For[i=1, i<l, i++, For[j=i+1, j<=l, j++, For[k=2, MemberQ[s, k*s[[j]]-(k-1)s[[i]]], k++, Null]; If[k>val, val=k]]]; val]; lap/@Divisors/@Range[1, 200]
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CROSSREFS
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Cf. A067132.
Sequence in context: A096859 A005086 A020649 this_sequence A094915 A081147 A083399
Adjacent sequences: A067128 A067129 A067130 this_sequence A067132 A067133 A067134
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KEYWORD
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easy,nonn
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Jan 09 2002
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EXTENSIONS
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Edited by Dean Hickerson (dean(AT)math.ucdavis.edu), Jan 15 2002
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