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A020878
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Number of one-factors in Moebius ladder M_n.
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2
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2, 3, 3, 6, 7, 13, 18, 31, 47, 78, 123, 201, 322, 523, 843, 1366, 2207, 3573, 5778, 9351, 15127, 24478, 39603, 64081, 103682, 167763, 271443, 439206, 710647, 1149853, 1860498, 3010351, 4870847, 7881198
(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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FORMULA
| if n mod 2 = 0 then L(n) else L(n)+2; fi; where L() are the Lucas numbers.
Empirical G.f.: (2+x-4*x^2-x^3)/((1+x)*(1-x)*(1-x-x^2)). [Colin Barker, Jan 23 2012]
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CROSSREFS
| A001350(n) + 2.
Sequence in context: A121833 A091606 A027037 * A158278 A187505 A027100
Adjacent sequences: A020875 A020876 A020877 * A020879 A020880 A020881
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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