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A144907
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a(n) = 1 if n is prime, 2 * rad(n) if four divides n and rad(n) otherwise.
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3
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1, 1, 1, 4, 1, 6, 1, 4, 3, 10, 1, 12, 1, 14, 15, 4, 1, 6, 1, 20, 21, 22, 1, 12, 5, 26, 3, 28, 1, 30, 1, 4, 33, 34, 35, 12, 1, 38, 39, 20, 1, 42, 1, 44, 15, 46, 1, 12, 7, 10, 51, 52, 1, 6, 55, 28, 57, 58, 1, 60, 1, 62, 21, 4, 65, 66, 1, 68, 69, 70, 1, 12, 1, 74, 15, 76, 77, 78, 1, 20, 3, 82
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OFFSET
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1,4
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LINKS
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MATHEMATICA
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rad[n_]:= Module[{aux = FactorInteger[n]}, Product[aux[[i, 1]], {i, Length[aux]}]]; a[n_] := Which[PrimeQ[n], 1, IntegerQ[n/4], 2*rad[n], True, rad[n]] Table[a[n], {n, 1, 100}] (* José María Grau Ribas, Feb 16 2010 *)
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PROG
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(Haskell)
a144907 x | a010051 x == 1 = 1
| x `mod` 4 == 0 = 2 * rad
| otherwise = rad where rad = a007947 x
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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STATUS
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approved
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