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a(1)=1; a(n)=a(n-1)+1 if n is in the sequence; a(n)=a(n-1)+2 if n and (n-1) are not in the sequence; a(n)=a(n-1)+3 if n is not in the sequence but (n-1) is in the sequence.
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%I #7 Mar 30 2012 18:39:18

%S 1,4,6,7,10,11,12,15,17,18,19,20,23,25,26,29,30,31,32,33,36,38,39,42,

%T 43,44,47,49,50,51,52,53,54,57,59,60,63,64,65,68,70,71,72,73,76,78,79,

%U 82,83,84,85,86,87,88,91,93,94,97,98,99,102,104,105,106,107,110,112,113

%N a(1)=1; a(n)=a(n-1)+1 if n is in the sequence; a(n)=a(n-1)+2 if n and (n-1) are not in the sequence; a(n)=a(n-1)+3 if n is not in the sequence but (n-1) is in the sequence.

%F a(n)=phi*n +O(1) where phi=(1+sqrt(5))/2

%K nonn

%O 1,2

%A _Benoit Cloitre_, Sep 13 2003

%E Corrected by _T. D. Noe_, Oct 25 2006