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%I #6 Oct 09 2013 14:20:53
%S 9,97,1349,20288,329707,5574248,97506021,1747201171,31923371982,
%T 592403479154
%N Number of ways to build a contiguous building with n LEGO blocks of size 2 X 2 on top of a fixed block of the same size.
%C The base block is not counted among the n and must be the only block in the bottom layer of the building
%Y Cf. A112389, A123762 - A123827, A123829 - A123849.
%K nonn,hard
%O 1,1
%A _Søren Eilers_, Oct 29 2006