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a(n) is the numerator of b(n) where b(n)=1/b(n-1)+1/b(n-2) with b(1)=1 and b(2)=2.
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%I #10 Jan 14 2023 17:50:39

%S 1,2,3,7,32,339,14287,6877760,143806067571,1372321205281802503,

%T 277081140489649960447116859520,

%U 544875880027767543589801386360499677678401262339

%N a(n) is the numerator of b(n) where b(n)=1/b(n-1)+1/b(n-2) with b(1)=1 and b(2)=2.

%F a(n) satisfies the cubic recurrence : a(1)=1, a(2)=2, a(3)=3, a(4)=7, a(5)=32 and for n>=6 a(n)=a(n-2)^2*a(n-3)+a(n-1)*a(n-3)*a(n-4).

%F Limit_{n->oo} b(n)=sqrt(2) with geometric convergence since abs(b(n)-sqrt(2))<2*2^(-n/2).

%Y Cf. A066932 (denominators).

%K nonn,frac

%O 1,2

%A _Zak Seidov_, Oct 24 2002

%E Edited by _Benoit Cloitre_, Oct 25 2005