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%I #5 Mar 30 2012 18:39:17
%S 1,3,2,6,18,4,12,36,3,9,27,7,21,63,19,57,171,5,15,45,13,39,117,37,111,
%T 333,4,12,36,10,30,90,28,84,252,8,24,72,22,66,198,64,192,576,20,60,
%U 180,58,174,522,172,516,1548,6,18,54,16,48,144,46,138,414,14,42,126,40,120
%N a(1)=1, a(n)=3*a(n-1) if n is not a multiple of 3, or a(n)=a(n/3)+1 if n is a multiple of 3.
%C b(1)=1, b(n)=3*b(n/3) if n is a multiple of 3, or b(n)=b(n-1)+1 if n is not a multiple of 3 produces the sequence 1, 2, 3, 4, ...
%o (PARI) a(n)=if(n<2,1,if(n%3,3*a(n-1),1+a(n/3)))
%K nonn
%O 1,2
%A _Benoit Cloitre_, May 04 2003