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%I #4 Mar 30 2012 17:20:57
%S 1,1,3,9,33,127,517,2173,9379,41295,184789,837903,3841603,17778605,
%T 82941987,389655675,1841797725,8752809573,41796432863,200446855069,
%U 965032948861,4662392162883,22597566894457,109845197218921
%N Recip transform of 2*(1 + x^3 + x^6)-1/(1-x).
%C Sign diagram of generating sequence: +--+--+--------...
%K nonn
%O 0,3
%A _Olivier Gérard_