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 A140259 a(0)=3; a(n)=A002264(n+11) if a(n-1)=1, a(n) = a(n-1)-1 if (n-1) mod 3 <> 0, otherwise a(n-1). 3

%I

%S 3,3,2,1,5,4,3,3,2,1,7,6,5,5,4,3,3,2,1,10,9,8,8,7,6,6,5,4,4,3,2,2,1,

%T 14,14,13,12,12,11,10,10,9,8,8,7,6,6,5,4,4,3,2,2,1,21,21,20,19,19,18,

%U 17,17,16,15,15,14,13,13,12,11,11,10,9,9,8,7,7,6,5,5,4,3,3,2,1,32,31

%N a(0)=3; a(n)=A002264(n+11) if a(n-1)=1, a(n) = a(n-1)-1 if (n-1) mod 3 <> 0, otherwise a(n-1).

%C Position of the knot after each iteration in Werneck's Black Pearl Necklace problem.

%H Nicolau Werneck, <a href="http://www.lti.pcs.usp.br/~nwerneck/adaptoide/">Adaptoide</a>, a library for adaptive finite automata. Source code in C++ available.

%H Nicolau Werneck, <a href="http://network.nature.com/blogs/user/nwerneck/2008/01/18/the-black-pearl-necklace">The Black Pearl Necklace</a>, description of the problem.

%H Nicolau Werneck, et al. <a href="http://forum.wolframscience.com/showthread.php?threadid=1506">Discussion on the NKS Forum</a>

%o (Scheme:) (define (A140259 n) (cond ((zero? n) 3) ((= 1 (A140259 (- n 1))) (A002264 (+ n 11))) ((not (zero? (modulo (- n 1) 3))) (- (A140259 (- n 1)) 1)) (else (A140259 (- n 1)))))

%Y Cf. A134342, A140260, A140261.

%K nonn

%O 0,1

%A _Antti Karttunen_, May 16 2008, based on the 2008 postings by Nicolau Leal Werneck (nwerneck(AT)gmail.com).

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Last modified February 22 17:35 EST 2019. Contains 320400 sequences. (Running on oeis4.)