a(n)=n-2*valuation(A000254(n),3). 1, 0, 3, 4, 5, 2, 1, 4, 5, 6, 7, 6, 7, 8, 7, 8, 9, 4, 5, 6, 3, 2, 5, 6, 7, 8, 7, 8, 9, 8, 9, 10, 9
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