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A254611
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Number of perfect matchings in the P_6 X C_n graph.
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1
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91, 1681, 2911, 28561, 79808, 591361, 2091817, 13344409, 53924597, 315169009, 1380947751, 7649951296, 35269184041, 188926707649, 899769503723, 4718266032649, 22943942934823, 118691459382721, 584955154102592, 2999832755191441, 14912246613880433, 76049269944443041, 380145205524781061
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OFFSET
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3,1
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LINKS
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Table of n, a(n) for n=3..25.
S. N. Perepechko, The number of perfect matchings in one kind of strip graphs (in Russian), Information Processes, 14 (2014), 340-356.
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FORMULA
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G.f. x^3*(91 + 1590*x - 4048*x^2 - 69300*x^3 + 50780*x^4 + 1164101*x^5 - 138254*x^6 - 10058547*x^7 - 1562576*x^8 + 50264529*x^9 + 13812974*x^10 - 155013203*x^11 - 47809304*x^12 + 306988809*x^13 + 89155840*x^14 - 399510007*x^15 - 96791692*x^16 + 345081045*x^17 + 62203726*x^18 - 197547813*x^19 - 23125568*x^20 + 74027795*x^21 + 4550826*x^22 - 17725337*x^23 - 329540*x^24 + 2608475*x^25 - 24182*x^26 - 221705*x^27 + 4727*x^28 + 9737*x^29 - 170*x^30 - 169*x^31)/((1 - x)*(1 + x)*(1 + 3*x - 4*x^2 + x^3)*(1 + 5*x + 6*x^2 + x^3)*(1 - 4*x + 3*x^2 + x^3)*(1 - 2*x - x^2 + x^3)*(1 - x - 2*x^2 + x^3)*(1 - 3*x - 4*x^2 -x^3)*(1 - 6*x + 5*x^2 - x^3)*(1 + 4*x + 3*x^2 - x^3)*(1 + 2*x - x^2 - x^3)*(1 + x - 2*x^2 - x^3)).
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CROSSREFS
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Cf. A068397, A102091, A252054, A253150.
Sequence in context: A333112 A140667 A221939 * A184462 A229518 A118706
Adjacent sequences: A254608 A254609 A254610 * A254612 A254613 A254614
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KEYWORD
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nonn,easy
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AUTHOR
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Sergey Perepechko, Feb 02 2015
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STATUS
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approved
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