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A082061
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Greatest common prime-divisor of n and phi(n)=A000010(n); a(n)=1 if no common prime-divisor was found.
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12
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1, 1, 1, 2, 1, 2, 1, 2, 3, 2, 1, 2, 1, 2, 1, 2, 1, 3, 1, 2, 3, 2, 1, 2, 5, 2, 3, 2, 1, 2, 1, 2, 1, 2, 1, 3, 1, 2, 3, 2, 1, 3, 1, 2, 3, 2, 1, 2, 7, 5, 1, 2, 1, 3, 5, 2, 3, 2, 1, 2, 1, 2, 3, 2, 1, 2, 1, 2, 1, 2, 1, 3, 1, 2, 5, 2, 1, 3, 1, 2, 3, 2, 1, 3, 1, 2, 1, 2, 1, 3, 1, 2, 3, 2, 1, 2, 1, 7, 3, 5, 1, 2, 1, 2, 3
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OFFSET
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1,4
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LINKS
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Table of n, a(n) for n=1..105.
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MAPLE
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gcpd := proc(a, b) local g , d ; g := 1 ; for d in numtheory[divisors](a) intersect numtheory[divisors](b) do if isprime(d) then g := max(g, d) ; end if; end do: g ; end proc:
A082061 := proc(n) gcpd( numtheory[phi](n), n) ; end proc: # R. J. Mathar, Jul 09 2011
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MATHEMATICA
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"factors/exponent SET "; ffi[x_] := Flatten[FactorInteger[x]] lf[x_] := Length[FactorInteger[x]] ba[x_] := Table[Part[ffi[x], 2*w-1], {w, 1, lf[x]}] f1[x_] := x; f2[x_] := EulerPhi[x] Table[Max[Intersection[ba[f1[w]], ba[f2[w]]]], {w, 1, 128}]
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PROG
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(PARI) gpf(n)=if(n>1, my(f=factor(n)[, 1]); f[#f], 1)
a(n)=gpf(gcd(eulerphi(n), n)) \\ Charles R Greathouse IV, Feb 19 2013
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CROSSREFS
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Cf. A000010, A006530.
Sequence in context: A094076 A089611 A082067 * A107286 A087039 A102096
Adjacent sequences: A082058 A082059 A082060 * A082062 A082063 A082064
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KEYWORD
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nonn
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu), Apr 07 2003
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STATUS
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approved
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