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A081327 Smallest 3-smooth number m such that n-m is also 3-smooth, a(n)=0 if no such 3-smooth number exists.

%I A081327 #8 Oct 14 2021 12:57:15
%S A081327 0,1,1,1,1,2,1,2,1,1,2,3,1,2,3,4,1,2,1,2,3,4,0,6,1,2,3,1,2,3,4,8,1,2,
%T A081327 3,4,1,2,3,4,9,6,16,8,9,0,0,12,1,2,3,4,0,6,1,2,3,4,27,6,0,8,9,16,1,2,
%U A081327 3,4,0,6,0,8,1,2,3,4,0,6,0,8,9,1,2,3,4,32,6,16,8,9,27,0,12,0,0,24,1,2,3,4,0
%N A081327 Smallest 3-smooth number m such that n-m is also 3-smooth, a(n)=0 if no such 3-smooth number exists.
%F A081327 a(n) = 0 iff A081326(n) = 0.
%F A081327 If a(n) > 0: a(n)+A081328(n) = n.
%e A081327 a(32) = 8 = 2^3, as 32 = 8 + 3*2^3.
%t A081327 smooth3Q[n_] := n/2^IntegerExponent[n, 2]/3^IntegerExponent[n, 3] == 1;
%t A081327 a[n_] := Module[{m}, For[m = 1, m<n, m++, If[smooth3Q[m] && smooth3Q[n-m], Return[m]]]; 0];
%t A081327 Table[a[n], {n, 1, 1000}] (* _Jean-François Alcover_, Oct 14 2021 *)
%Y A081327 Cf. A081329, A081330, A081328, A000040, A003586.
%K A081327 nonn
%O A081327 1,6
%A A081327 _Reinhard Zumkeller_, Mar 19 2003