A028455 Number of perfect matchings in graph P_{2} X C_{3} X P_{n}.

1, 4, 50, 444, 4349, 41348, 396733, 3795912, 36350866, 348013000, 3332060177, 31902067752, 305441725601, 2924400160544, 27999196885618, 268073721835248, 2566628109851821, 24573761479828684, 235277465932911917, 2252625667246251996, 21567396521342873618

Offset

0,2

Links

Alois P. Heinz, Table of n, a(n) for n = 0..1000

Per Hakan Lundow, Computation of matching polynomials and the number of 1-factors in polygraphs, Research report, No 12, 1996, Department of Math., Umea University, Sweden.

Per Hakan Lundow, Enumeration of matchings in polygraphs, 1998.

Formula

G.f.: (x^6 +4*x^5 -4*x^4 -16*x^3 +4*x^2 +4*x -1) / (-x^8 -8*x^7 +22*x^6 +60*x^5 -67*x^4 -60*x^3 +22*x^2 +8*x -1). - Alois P. Heinz, Dec 09 2013

Crossrefs

Sequence in context: A219566 A202790 A231833 * A232731 A215792 A280358

Adjacent sequences: A028452 A028453 A028454 * A028456 A028457 A028458

Keyword

nonn

Author

Per H. Lundow

Status

approved