

A028474


Number of perfect matchings in graph P_{12} X P_{n}.


4



1, 1, 233, 2131, 145601, 2332097, 106912793, 2188978117, 82741005829, 1937528668711, 65743732590821, 1666961188795475, 53060477521960000, 1412218550274852671, 43242613716069407953, 1185802123987680144427, 35457442115448212075033, 990424779934371836605849
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OFFSET

0,3


LINKS

Table of n, a(n) for n=0..17.
Per Hakan Lundow, Computation of matching polynomials and the number of 1factors in polygraphs, Research report, No 12, 1996, Department of Math., Umea University, Sweden.
Per Hakan Lundow, Enumeration of matchings in polygraphs, 1998.
Sergey Perepechko, Generation function


MATHEMATICA

t[m_, n_] := Product[2*(2 + Cos[2*j*Pi/(m+1)] + Cos[2*k*Pi/(n+1)]), {k, 1, n/2}, {j, 1, m/2}]; a[n_] := N[t[n, 12], 16] // Round; Table[a[n], {n, 1, 15}] (* JeanFrançois Alcover, Dec 20 2012, after A099390 *)


PROG

(PARI) {a(n) = sqrtint(polresultant(polchebyshev(12, 2, x/2), polchebyshev(n, 2, I*x/2)))} \\ Seiichi Manyama, Apr 13 2020


CROSSREFS

Row 12 of array A099390.
Sequence in context: A230392 A003537 A037033 * A101218 A250464 A221812
Adjacent sequences: A028471 A028472 A028473 * A028475 A028476 A028477


KEYWORD

nonn


AUTHOR

Per H. Lundow


STATUS

approved



