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A083481
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Squarefree part of the n-th oblong number.
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5
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2, 6, 3, 5, 30, 42, 14, 2, 10, 110, 33, 39, 182, 210, 15, 17, 34, 38, 95, 105, 462, 506, 138, 6, 26, 78, 21, 203, 870, 930, 62, 66, 1122, 1190, 35, 37, 1406, 1482, 390, 410, 1722, 1806, 473, 55, 230, 2162, 141, 3, 2, 102, 663, 689, 318, 330, 770, 798, 3306, 3422, 885
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OFFSET
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1,1
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COMMENTS
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Smallest k such that n*(n+1)*k is a perfect square.
k = p*q*r... is a squarefree number where p,q,r are those prime factors of n(n+1) which have odd index.
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LINKS
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FORMULA
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MAPLE
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end proc:
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MATHEMATICA
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sk[n_]:=Module[{k=1}, While[!IntegerQ[Sqrt[n*k]], k++]; k]; sk/@Table[n(n+1), {n, 60}] (* Harvey P. Dale, Mar 28 2013 *)
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PROG
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(PARI) a(n)=core(n*(n+1))
(Python)
from sympy.ntheory.factor_ import core
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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Amarnath Murthy and Meenakshi Srikanth (menakan_s(AT)yahoo.com), May 03 2003
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EXTENSIONS
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STATUS
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approved
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