A123789 - OEIS

A123789

Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 1 X 5 which is flat, i.e., with all blocks in parallel position and symmetric after a rotation by 180 degrees.

%I #12 Sep 12 2018 05:30:20

%S 1,1,5,7,49,77,572,949,7245,12361,96063,167564,1313467,2327488,

%T 18365795,32936281,261111133,472694546

%N Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 1 X 5 which is flat, i.e., with all blocks in parallel position and symmetric after a rotation by 180 degrees.

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

%K nonn,more

%O 1,3

%A _Søren Eilers_, Oct 29 2006

%E More terms by _Søren Eilers_, Sep 12 2018