2,1

Fault-free tilings are those where the only straight interface is at the left and right end. Thus a(n) <= A084478(n).

C. Moore, [math/9905012] Some Polyomino Tilings of the Plane

M. Aanjaneya and S. P. Pal, Faultfree tromino tilings of rectangles

G.f. 24z^2(3+10z+15z^2)/(1-2z-31z^2-40z^3-20z^4).

Cf. A084478, A084477, A084480, A084481.

Adjacent sequences: A084476 A084477 A084478 this_sequence A084480 A084481 A084482

Sequence in context: A004007 A107314 A090788 this_sequence A084478 A085718 A077120

nonn,easy

Ralf Stephan (ralf(AT)ark.in-berlin.de), May 27 2003