login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A028448 Number of perfect matchings in graph P_{2} X P_{4} X P_{n}. 2
1, 5, 121, 1845, 32000, 535229, 9049169, 152526845, 2573281769, 43402320448, 732106008249, 12348802743437, 208295014563521, 3513435627771565, 59263242055245056, 999628735946792581, 16861339891166667849, 284410369641222811445, 4797320930581855672689 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..800

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^19 +17*x^18 -53*x^17 -383*x^16 +2051*x^15 +1155*x^14 -16891*x^13 +9523*x^12 +45157*x^11 -41065*x^10 -41065*x^9 +45157*x^8 +9523*x^7 -16891*x^6 +1155*x^5 +2051*x^4 -383*x^3 -53*x^2 +17*x -1) / (x^21 -22*x^20 +42*x^19 +990*x^18 -3493*x^17 -12199*x^16 +55858*x^15 +27106*x^14 -289337*x^13 +146481*x^12 +488514*x^11 -488514*x^10 -146481*x^9 +289337*x^8 -27106*x^7 -55858*x^6 +12199*x^5 +3493*x^4 -990*x^3 -42*x^2 +22*x -1). - Alois P. Heinz, Dec 08 2013

CROSSREFS

Column k=4 of A181206.

Sequence in context: A054752 A258978 A128275 * A108791 A282271 A179299

Adjacent sequences:  A028445 A028446 A028447 * A028449 A028450 A028451

KEYWORD

nonn

AUTHOR

Per H. Lundow

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 11 02:27 EDT 2021. Contains 342886 sequences. (Running on oeis4.)