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A152166
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a(2*n)=2^n ; a(2*n+1)=-(2^(n+1)).
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4
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1, -2, 2, -4, 4, -8, 8, -16, 16, -32, 32, -64, 64, -128, 128, -256, 256, -512, 512, -1024, 1024, -2048, 2048, -4096, 4096, -8192, 8192, -16384, 16384, -32768, 32768, -65536, 65536, -131072, 131072, -262144, 262144, -524288, 524288, -1048576, 1048576
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| Ratios of successive terms are -2,-1,-2,-1,-2,-1,-2,-1,... [From Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Dec 12 2008]
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FORMULA
| G.f.: (1-2*x)/(1-2*x^2). a(n)=2*a(n-2); a(0)=1, a(1)=-2 . a(n)=Sum{k, 0<=k<=n}A147703(n,k)*(-3)^k.
a(n)=(3/4)*8^(1/4)*(-1)^n*2^[(1/2)*n]*2^[(1/4)*(-1)^n]-(1/4)*8^(1/4)*2^[(1/2)*n]*2^[(1/4)*(-1)^n], with n>=0 [From Paolo P. Lava (paoloplava(AT)gmail.com), Dec 01 2008]
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CROSSREFS
| Cf. A000079, A016116
Sequence in context: A158780 A117575 A131572 * A016116 A060546 A163403
Adjacent sequences: A152163 A152164 A152165 * A152167 A152168 A152169
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KEYWORD
| sign
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AUTHOR
| Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Nov 27 2008
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