A033526 Number of matchings in graph P_{2} X P_{3} X P_{n}.

1, 22, 1511, 90040, 5493583, 334056618, 20324827981, 1236501116120, 75226160041933, 4576591071807054, 278429681683117411, 16939044773645481920, 1030533959174319758227, 62695402974582513118434, 3814249420035058238741393, 232050484511869215926762256

Offset

0,2

References

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

Links

Alois P. Heinz, Table of n, a(n) for n = 0..500

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

Formula

G.f.: (-x^22 +2*x^21 +105*x^20 -408*x^19 -2333*x^18 +11980*x^17 +12081*x^16 -112640*x^15 +25122*x^14 +435060*x^13 -292630*x^12 -741024*x^11 +647902*x^10 +512680*x^9 -535258*x^8 -85184*x^7 +168951*x^6 -24902*x^5 -12107*x^4 +3384*x^3 -57*x^2 -36*x +1) / (x^24 -4*x^23 -148*x^22 +636*x^21 +5486*x^20 -25774*x^19 -66616*x^18 +377290*x^17 +207927*x^16 -2210908*x^15 +370396*x^14 +5950068*x^13 -2989756*x^12 -7411696*x^11 +5362636*x^10 +3624000*x^9 -3734313*x^8 -139824*x^7 +897064*x^6 -240512*x^5 -5090*x^4 +7406*x^3 -292*x^2 -58*x +1). - Alois P. Heinz, Dec 09 2013

Crossrefs

Sequence in context: A348813 A160309 A367369 * A078399 A243478 A245658

Adjacent sequences: A033523 A033524 A033525 * A033527 A033528 A033529

Keyword

nonn

Author

Per H. Lundow

Status

approved