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Search: id:A138340
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| A138340 |
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Expansion of (1-8x)/(1-4x+16x^2). |
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+0
3
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| 1, -4, -32, -64, 256, 2048, 4096, -16384, -131072, -262144, 1048576, 8388608, 16777216, -67108864, -536870912, -1073741824, 4294967296, 34359738368, 68719476736, -274877906944, -2199023255552, -4398046511104, 17592186044416
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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abs(a(n))=2^A047267(n).
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FORMULA
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a(n):=2*4^n(cos(pi*(n+1)/3)-sqrt(3)*sin(pi*(n+1))/3);
a(n)=4^n*Sum_{k, 0<=k<=n} A121314(n,k)*(-1)^k*3^(n-k). [From Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Nov 01 2008]
a(n)=A128018(n)*2^n. [From Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Nov 14 2008]
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CROSSREFS
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Sequence in context: A114076 A078092 A076137 this_sequence A113250 A012036 A153794
Adjacent sequences: A138337 A138338 A138339 this_sequence A138341 A138342 A138343
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KEYWORD
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easy,sign
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AUTHOR
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Paul Barry (pbarry(AT)wit.ie), Mar 15 2008
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