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%I #21 Apr 02 2024 12:49:03
%S 1,1,2,6,21,224,10848,4843293,98262557120,989063619297120960,
%T 197348115975871052843094930213,
%U 380244324677612882673067751880150651746235378560
%N a(n) is the denominator of b(n) where b(n)=1/b(n-1)+1/b(n-2) with b(1)=1 and b(2)=2.
%C Limit_{n->oo} b(n)=sqrt(2) with geometric convergence since abs(b(n)-sqrt(2))<2*2^(-n/2)
%F a(n+1) = A057677(n)*A057677(n-1). - _Benoit Cloitre_, Oct 25 2005
%F a(n) is the numerator of c(n) where c(n)=1/(c(n-1)+c(n-2)) with c(0)=c(1)=1. - _Mark Dols_, Jul 17 2009
%t nxt[{a_,b_}]:={b,1/a+1/b}; NestList[nxt,{1,2},20][[;;,1]]//Denominator (* _Harvey P. Dale_, Apr 02 2024 *)
%Y Cf. A057677 (numerator), A074937, A162924, A162926.
%K nonn,frac
%O 1,3
%A _Zak Seidov_, Oct 24 2002
%E Edited by _Benoit Cloitre_, Oct 25 2005