40209

Appears in sequences

• 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 and symmetric after a rotation by 180 degrees.at n=10A123781
• a(n) = 324*n^2 - 564*n + 321 (n>=1).at n=11A304617
• Expansion of -1/(1 - x)^2 + (1/(1 - x))*Product_{k>=1} (1 + x^k).at n=52A317910