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Search: id:A164111
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| A164111 |
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Expansion of (1-x)/(1+4x^2). |
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+0
2
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| 1, -1, -4, 4, 16, -16, -64, 64, 256, -256, -1024, 1024, 4096, -4096, -16384, 16384, 65536, -65536, -262144, 262144, 1048576, -1048576, -4194304, 4194304, 16777216, -16777216, -67108864, 67108864, 268435456, -268435456, -1073741824
(list; graph; listen)
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OFFSET
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0,3
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COMMENT
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Hankel transform of 1,1,0,2,0,6,0,70,... (which has g.f. 1+x/sqrt(1-4x^2). See A126869).
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FORMULA
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a(n)=(-1)^C(n+1,2)*(4^(n/2)*(1+(-1)^n)/2+4^((n-1)/2)(1-(-1)^n)/2).
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CROSSREFS
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Sequence in context: A125757 A056450 A141125 this_sequence A164906 A129884 A137725
Adjacent sequences: A164108 A164109 A164110 this_sequence A164112 A164113 A164114
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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), Aug 10 2009
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