A123780 - OEIS

A123780

Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 1 X 4 which is flat, i.e., with all blocks in parallel position.

%I #7 Jul 21 2017 15:38:06

%S 1,4,33,294,2951,30668,328999,3596934,39932206,448517488,5086259884,

%T 58135266335

%N Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 1 X 4 which is flat, i.e., with all blocks in parallel position.

%Y Cf. A112389, A123762 - A123827, A123829 - A123849.

%K nonn,hard

%O 1,2

%A _Søren Eilers_, Oct 29 2006