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A115017
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a(n) = largest triangular number dividing n.
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2
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1, 1, 3, 1, 1, 6, 1, 1, 3, 10, 1, 6, 1, 1, 15, 1, 1, 6, 1, 10, 21, 1, 1, 6, 1, 1, 3, 28, 1, 15, 1, 1, 3, 1, 1, 36, 1, 1, 3, 10, 1, 21, 1, 1, 45, 1, 1, 6, 1, 10, 3, 1, 1, 6, 55, 28, 3, 1, 1, 15, 1, 1, 21, 1, 1, 66, 1, 1, 3, 10, 1, 36, 1, 1, 15, 1, 1, 78, 1, 10, 3, 1, 1, 28, 1, 1, 3, 1, 1, 45, 91, 1, 3, 1
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OFFSET
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1,3
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LINKS
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FORMULA
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EXAMPLE
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a(12)=6 because the triangular numbers dividing 12 are 1,3 and 6.
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MAPLE
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a:=proc(n) local P, j; P:={}: for j from 1 to n do if type(n/(j*(j+1)/2), integer)=true then P:=P union {j*(j+1)/2} else P:=P: fi od: P[nops(P)]; end: seq(a(n), n=1..105); # Emeric Deutsch, Mar 01 2006
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MATHEMATICA
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With[{trnos=Accumulate[Range[100]]}, Table[Last[Select[trnos, Divisible[ n, #]&]], {n, 100}]] (* Harvey P. Dale, Nov 08 2011 *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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