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A117373
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Expansion of (1-3x)/(1-x+x^2).
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9
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1, -2, -3, -1, 2, 3, 1, -2, -3, -1, 2, 3, 1, -2, -3, -1, 2, 3, 1, -2, -3, -1, 2, 3, 1, -2, -3, -1, 2, 3, 1, -2, -3, -1, 2, 3, 1, -2, -3, -1, 2, 3, 1, -2, -3, -1, 2, 3, 1, -2, -3, -1, 2, 3, 1
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| Row sums of number triangle A117372.
Periodic sequence with period {1, -2, -3, -1, 2, 3}. [From Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Nov 03 2008]
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LINKS
| Index entries for sequences related to linear recurrences with constant coefficients
Tanya Khovanova, Recursive Sequences
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FORMULA
| a(n)=sum{k=0..n, (-1)^(n-k)(C(k,n-k)+3*C(k, n-k-1))}
a(n)=1/6*{2*[n mod 6]-[(n+1) mod 6]-3*[(n+2) mod 6]-2*[(n+3) mod 6]+[(n+4) mod 6]+3*[(n+5) mod 6]}, with n>=1. - Paolo P. Lava (paoloplava(AT)gmail.com), Apr 27 2007
a(n)=a(n-1)-a(n-2); a(0)=1, a(1)=-2 . [From Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Nov 03 2008]
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MATHEMATICA
| CoefficientList[Series[(1 - 3 x)/(1 - x + x^2), {x, 0, 200}], x] (* From Vladimir Joseph Stephan Orlovsky, Jun 11 2011 *)
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CROSSREFS
| Sequence in context: A073645 A179542 A082846 * A132677 A010882 A106590
Adjacent sequences: A117370 A117371 A117372 * A117374 A117375 A117376
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KEYWORD
| easy,sign
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AUTHOR
| Paul Barry (pbarry(AT)wit.ie), Mar 10 2006
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