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Search: id:A102276
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| A102276 |
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Sequence defined by recursion derived from a genus 2 curve. |
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+0
1
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| 1, 1, 1, 1, 1, 1, 2, 3, 4, 8, 17, 50, 107, 239, 1103, 3775, 14463, 55283, 256666, 2059753, 9820288, 55075036, 503857819, 4083736906, 44590046729, 335845998321, 3581731774609, 68868876045617, 782035904796497, 11680434156713849
(list; graph; listen)
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OFFSET
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0,7
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LINKS
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A. J. van der Poorten, Curves of Genus 2, Continued Fractions, and Somos Sequences, J. Integer Seqs., 8 (2005), #05.3.4.
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FORMULA
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a(n)=(a(n-1)a(n-5)+a(n-3)^2)/a(n-6). a(0)=...=a(5)=1. a(n)=a(5-n).
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PROGRAM
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(PARI) a(n)=local(an); if(n<0, a(5-n), n++; an=vector(n, i, 1); for(k=7, n, an[k]=(an[k-1]*an[k-5]+an[k-3]^2)/an[k-6]); an[n])
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CROSSREFS
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Cf. A006720, A006722.
Sequence in context: A122774 A118841 A126294 this_sequence A105055 A108506 A129284
Adjacent sequences: A102273 A102274 A102275 this_sequence A102277 A102278 A102279
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KEYWORD
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nonn
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AUTHOR
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Michael Somos, Jan 02 2005
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