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a(1)=1, a(2)=2, a(n)=2*a(n-2)*a(n-1)-a(n-1).
2

%I #5 Nov 21 2013 12:49:59

%S 1,2,2,6,18,198,6930,2737350,37936933650,207693292716721350,

%T 15758493330480878908260133650,

%U 6545866736124132578837836330405530973356721350

%N a(1)=1, a(2)=2, a(n)=2*a(n-2)*a(n-1)-a(n-1).

%t a=1;b=2;lst={a,b};Do[c=2*a*b-b;AppendTo[lst,c];a=b;b=c,{n,12}];lst

%t RecurrenceTable[{a[1]==1,a[2]==2,a[n]==2a[n-2]a[n-1]-a[n-1]},a,{n,14}] (* _Harvey P. Dale_, Jan 27 2012 *)

%Y Cf. A173093, A173094, A173096, A173097

%K nonn

%O 1,2

%A _Vladimir Joseph Stephan Orlovsky_, Feb 09 2010