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A020873
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Number of cycles in Moebius ladder M_n.
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0
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2, 3, 7, 15, 29, 53, 95, 171, 313, 585, 1115, 2159, 4229, 8349, 16567, 32979, 65777, 131345, 262451, 524631, 1048957, 2097573, 4194767, 8389115, 16777769, 33555033, 67109515, 134218431, 268436213
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,1
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REFERENCES
| J. P. McSorley, Counting structures in the Moebius ladder, Discrete Math., 184 (1998), 137-164.
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LINKS
| Index to sequences with linear recurrences with constant coefficients, signature (5,-9,7,-2). [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), May 31 2010]
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FORMULA
| 2^n+n^2-n+1.
a(n)= +5*a(n-1) -9*a(n-2) +7*a(n-3) -2*a(n-4). G.f.: ( 2-7*x+10*x^2-7*x^3 ) / ( (2*x-1)*(x-1)^3 ). [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), May 31 2010]
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MATHEMATICA
| Table[2^n+n^2-n+1, {n, 0, 5!}] [From Vladimir Orlovsky (4vladimir(AT)gmail.com), May 07 2010]
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CROSSREFS
| Sequence in context: A001276 A006884 A074742 * A049958 A177487 A153010
Adjacent sequences: A020870 A020871 A020872 * A020874 A020875 A020876
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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