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Search: id:A156232
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| A156232 |
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a(n) is the number of induced subgraphs with odd number of edges in the cycle graph C(n) |
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+0
2
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| 0, 4, 4, 16, 24, 64, 112, 256, 480, 1024, 1984, 4096, 8064, 16384, 32512, 65536, 130560, 262144, 523264, 1048576, 2095104, 4194304, 8384512, 16777216, 33546240, 67108864, 134201344, 268435456, 536838144, 1073741824, 2147418112
(list; graph; listen)
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OFFSET
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2,2
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FORMULA
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a(n) = 2^(n-1)-2^(n/2) if n is even, 2^(n-1) otherwise
G.f.: 4x^3(1-x)/((1-2x)(1-2x^2)). a(n)=2*a(n-1)+2*a(n-2)-4*a(n-3). [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Feb 10 2009]
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CROSSREFS
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A000749, A141447
Sequence in context: A129884 A137725 A082649 this_sequence A053441 A065732 A092959
Adjacent sequences: A156229 A156230 A156231 this_sequence A156233 A156234 A156235
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KEYWORD
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nonn
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AUTHOR
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Alessandro Cosentino (cosenal(AT)gmail.com), Feb 06 2009
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EXTENSIONS
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More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Feb 10 2009
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