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A126023 a(0)=0, a(1)=1; for n>1, a(n) = a(n-1)*(a(n-1)+a(n-2)).

%I A126023 #17 Jun 02 2017 12:27:45
%S A126023 0,1,1,2,6,48,2592,6842880,46842743439360,
%T A126023 2194242933464976548324966400,
%U A126023 4814702051061088283920560140388303599459408453566464000,23181355840491850372772514246989811472332466216882815765831029699284672633019505150499832539732598430105600000
%N A126023 a(0)=0, a(1)=1; for n>1, a(n) = a(n-1)*(a(n-1)+a(n-2)).
%H A126023 Steven R. Finch, <a href="/A072042/a072042.pdf">Substitution dynamics</a>, January 23, 2014. [Cached copy, with permission of the author]
%H A126023 <a href="/index/Aa#AHSL">Index entries for sequences of form a(n+1)=a(n)^2 + ...</a>
%F A126023 a(n) ~ c^(2^n), where c = 1.130839439573188327984771046199629891088102083459871373699856783789557668... . - _Vaclav Kotesovec_, Dec 18 2014
%t A126023 a=0;b=1;lst={a,b};Do[c=(a+b)*b;AppendTo[lst,c];a=b;b=c,{n,2*3!}];lst (* _Vladimir Joseph Stephan Orlovsky_, Sep 05 2009 *)
%t A126023 RecurrenceTable[{a[0]==0, a[1]==1, a[n] == a[n-1]*(a[n-1]+a[n-2])}, a, {n, 0, 10}] (* _Vaclav Kotesovec_, Dec 18 2014 *)
%o A126023 (PARI) a=0;b=1;vector(11,i,c=b*(b+a);a=b;b=c;a)
%Y A126023 Cf. A064183.
%K A126023 easy,nonn
%O A126023 0,4
%A A126023 _Franklin T. Adams-Watters_, Feb 27 2007