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A167380
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a(1)=1, a(2)=2, and continued periodically with 4, 5, 1, -4, -5, -1 .
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3
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1, 2, 4, 5, 1, -4, -5, -1, 4, 5, 1, -4, -5, -1, 4, 5, 1, -4, -5, -1, 4, 5, 1, -4, -5, -1, 4, 5, 1, -4, -5, -1, 4, 5, 1, -4, -5, -1, 4, 5, 1, -4, -5, -1, 4, 5, 1, -4, -5, -1, 4, 5, 1, -4, -5, -1, 4, 5, 1, -4, -5, -1, 4, 5, 1, -4, -5, -1, 4, 5, 1, -4, -5, -1, 4, 5, 1, -4, -5, -1, 4, 5, 1, -4, -5
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OFFSET
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1,2
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LINKS
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FORMULA
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a(1)=1. a(2)=2. a(6k-3)=4. a(6k-2)=5. a(6k-1)=1. a(6k)=-4. a(6k+1)=-5. a(6k+2)=-1.
a(n) = a(n-1) - a(n-2), n > 4.
G.f.: x*(1+x)*(3*x^2+1)/(1-x+x^2). (End)
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MAPLE
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A167380 := proc(n) if n <= 2 then n; else op(1+ (n mod 6), [-4, -5, -1, 4, 5, 1]) ; end if; end proc: seq(A167380(n), n=1..120) ; # R. J. Mathar, Nov 02 2009
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MATHEMATICA
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PadRight[{1, 2}, 120, {-5, -1, 4, 5, 1, -4}] (* or *) Join[{1, 2}, LinearRecurrence[ {1, -1}, {4, 5}, 120]] (* Harvey P. Dale, Mar 08 2015 *)
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CROSSREFS
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KEYWORD
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sign,easy
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AUTHOR
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EXTENSIONS
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Unrelated material removed, and values corrected according to definition, by R. J. Mathar, Nov 05 2009
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STATUS
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approved
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