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A115360
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Periodic {1,-1,1,0,0,0}.
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2
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1, -1, 1, 0, 0, 0, 1, -1, 1, 0, 0, 0, 1, -1, 1, 0, 0, 0, 1, -1, 1, 0, 0, 0, 1, -1, 1, 0, 0, 0, 1, -1, 1, 0, 0, 0, 1, -1, 1, 0, 0, 0, 1, -1, 1, 0, 0, 0, 1, -1, 1, 0, 0, 0, 1, -1, 1, 0, 0, 0, 1, -1, 1, 0, 0, 0, 1, -1, 1, 0, 0, 0
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,1
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COMMENTS
| Diagonal sums of number triangle A115359.
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FORMULA
| G.f.: 1/(1+x-x^3-x^4); a(n)=-a(n-1)+a(n-3)+a(n-4); a(n)=cos(2*pi*n/3)/3-sin(2*pi*n/3)/sqrt(3)+cos(pi*n)/2+1/6; a(n)=sum{k=0..floor(n/2), if(n-k=k, 1, 0) OR if(n-k=2k+1, -1, 0)}.
a(n)=(1/90)*{-14*(n mod 6)+[(n+1) mod 6]+[(n+2) mod 6]+16*[(n+3) mod 6]-29*[(n+4) mod 6]+31*[(n+5) mod 6]}, with n>=0 - Paolo P. Lava (paoloplava(AT)gmail.com), Jun 11 2007
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CROSSREFS
| Sequence in context: A068431 A143466 A117908 * A088911 A179763 A105349
Adjacent sequences: A115357 A115358 A115359 * A115361 A115362 A115363
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KEYWORD
| easy,sign
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AUTHOR
| Paul Barry (pbarry(AT)wit.ie), Jan 21 2006
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