A123811 Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 1 X 8 which is symmetric after a rotation by 180 degrees.
1, 1, 73, 893, 11257, 167129, 1969619
Offset: 1
This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.