%I #4 Mar 31 2012 20:30:53
%S 1,1,2,2,2,2,3,2,4,4,5,5,4,5,8,6,7,6,8,7,9,8,6,5,6,7,10,10,11,12,13,
%T 12,11,11,11,9,10,13,14,14,14,13,15,15,15,13,13,13,16,19,20,19,19,14,
%U 17,20,21,19,20,23,20,19,21,24,22,21,20,21,24,24,22,21,23,22,23,23,27,25,33
%N Half of the digital sum of base 3 representations of 2^n.
%e 2^4=16={1,2,1} (base 3) ==> a(4)=(1+2+1)/2 =2
%t a[n_] := 1/2* Module[{aux = IntegerDigits[2^n,3]}, Sum[aux[[i]], {i, 1, Length[aux]}]]; Table[a[n], {n, 100}]
%K nonn,base
%O 1,3
%A _José María Grau Ribas_, Apr 02 2010