A144907 a(n) = 1 if n is prime, 2 * rad(n) if four divides n and rad(n) otherwise.

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

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 A354254

Adjacent sequences: A144904 A144905 A144906 * A144908 A144909 A144910

Keyword

easy,nonn

Author

Reikku Kulon, Sep 24 2008

Status

approved