0,3

Form a graph from a triangle and its midpoint triangle. A093044 counts closed walks of length n at a vertex of the original triangle.

G.f.: (1-x-5x^2-2x^3)/((1+x-x^2)(1-2x-4x^2)); a(n)=A078008(n)*A000045(n-1); a(n)=(2^n/3+2(-1)^n/3)(((1+sqrt(5))/2)^(n-1)/sqrt(5)-((1-sqrt(5))/2)^(n-1)/sqrt(5)).

Sequence in context: A131384 A052612 A130306 this_sequence A033886 A087131 A131444

Adjacent sequences: A093041 A093042 A093043 this_sequence A093045 A093046 A093047

easy,nonn

Paul Barry (pbarry(AT)wit.ie), Mar 22 2004