A254611 Number of perfect matchings in the P_6 X C_n graph.

91, 1681, 2911, 28561, 79808, 591361, 2091817, 13344409, 53924597, 315169009, 1380947751, 7649951296, 35269184041, 188926707649, 899769503723, 4718266032649, 22943942934823, 118691459382721, 584955154102592, 2999832755191441, 14912246613880433, 76049269944443041, 380145205524781061

Offset

3,1

Links

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.

Formula

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)).

Crossrefs

Cf. A068397, A102091, A252054, A253150.

Sequence in context: A333112 A140667 A221939 * A184462 A229518 A118706

Adjacent sequences: A254608 A254609 A254610 * A254612 A254613 A254614

Keyword

nonn,easy

Author

Sergey Perepechko, Feb 02 2015

Status

approved