A103998 Number of dimer tilings of a 4 x 2n Moebius strip.

1, 11, 71, 539, 4271, 34276, 276119, 2226851, 17965151, 144948419, 1169523076, 9436433171, 76139155439, 614339685971, 4956888901511, 39995380044004, 322708555336511, 2603821045832171, 21009309912323639

Offset: 0

Author

Ralf Stephan, Feb 26 2005

Keywords

• nonn

Links

• Index entries for linear recurrences with constant coefficients, signature (11, -25, 11, -1).

Crossrefs

Cf. Second row of array A103997.

Programs

Mathematica

Join[{1},LinearRecurrence[{11,-25,11,-1},{11,71,539,4271},40]] (* or *) CoefficientList[ Series[ (1-25x^2+22x^3-3x^4)/ (1-11x+ 25x^2- 11x^3+x^4),{x,0,40}],x] (* Harvey P. Dale, Jun 15 2011 *)

Formula

G.f.: (1-25x^2+22x^3-3x^4)/(1-11x+25x^2-11x^3+x^4).

a(0)=1, a(1)=11, a(2)=71, a(3)=539, a(4)=4271, a(n)=11*a(n-1)-25*a(n-2)+ 11*a(n-3)-a(n-4). - Harvey P. Dale, Jun 15 2011