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A144907 a(n) = 1 if n is prime, 2 * rad(n) if four divides n and rad(n) otherwise. 3
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Reikku Kulon, Table of n, a(n) for n = 1..10000

MATHEMATICA

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 *)

PROG

(Haskell)

a144907 x | a010051 x == 1 = 1

          | x `mod` 4 == 0 = 2 * rad

          | otherwise      = rad  where rad = a007947 x

-- Reinhard Zumkeller, Mar 12 2014

CROSSREFS

Cf. A000040, A007947, A144100, A144310.

Sequence in context: A257656 A109040 A133828 * A185093 A010779 A215619

Adjacent sequences:  A144904 A144905 A144906 * A144908 A144909 A144910

KEYWORD

easy,nonn

AUTHOR

Reikku Kulon, Sep 24 2008

STATUS

approved

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Last modified February 25 14:40 EST 2021. Contains 341609 sequences. (Running on oeis4.)