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Search: id:A072175
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| A072175 |
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a(1)=1, a(2)=2, a(n) = a(n-1) + 1 - 2*sign(a(n-2)) for n>2. |
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+0
1
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| 1, 2, 1, 0, -1, 0, 3, 4, 3, 2, 1, 0, -1, 0, 3, 4, 3, 2, 1, 0, -1, 0, 3, 4, 3, 2, 1, 0, -1, 0, 3, 4, 3, 2, 1, 0, -1, 0, 3, 4, 3, 2, 1, 0, -1, 0, 3, 4, 3, 2, 1, 0, -1, 0, 3, 4, 3, 2, 1, 0, -1, 0, 3, 4, 3, 2, 1, 0, -1, 0, 3, 4, 3, 2, 1, 0, -1, 0, 3, 4, 3, 2, 1, 0, -1, 0, 3, 4, 3, 2, 1, 0, -1, 0, 3, 4, 3, 2, 1, 0, -1, 0, 3, 4, 3
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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The sequence has period 8 except for the first term.
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REFERENCES
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Marius-F. Danca, Contributions to the Theory of Discontinuous Dynamical System, Thesis 2002, University Babes-Bolyai, Cluj, Romania, page 5
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FORMULA
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a(n)=(1/28)*{5*(n mod 8)-2*[(n+1) mod 8]-9*[(n+2) mod 8]-2*[(n+3) mod 8]+5*[(n+4) mod 8]+5*[(n+5) mod 8]+5*[(n+6) mod 8]+5*[(n+7) mod 8]}-2*[C(2*n,n) mod 2], with n>=0 [From Paolo P. Lava (ppl(AT)spl.at), Aug 06 2009]
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EXAMPLE
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a(3)=2+1-2*sign(1)=1. a(4)=1+1-2*sign(2)=0.
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MATHEMATICA
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a[1]=1; a[2]=2; a[n_] := a[n]=a[n-1]+1-2Sign[a[n-2]]
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CROSSREFS
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Sequence in context: A116675 A123022 A072943 this_sequence A092147 A143240 A153659
Adjacent sequences: A072172 A072173 A072174 this_sequence A072176 A072177 A072178
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KEYWORD
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sign
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AUTHOR
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Roger L. Bagula (rlbagulatftn(AT)yahoo.com), Jun 29 2002
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EXTENSIONS
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Edited by Dean Hickerson (dean.hickerson(AT)yahoo.com), Jul 31 2002
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