A123804 Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 1 X 7 which is flat, i.e., with all blocks in parallel position.

1, 7, 109, 1877, 35243, 685817, 13719483, 279714347, 5788634457

Offset

1,2

Links

Table of n, a(n) for n=1..9.

Crossrefs

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

Sequence in context: A142480 A202515 A096498 * A333092 A274668 A239848

Adjacent sequences: A123801 A123802 A123803 * A123805 A123806 A123807

Keyword

nonn,hard

Author

Søren Eilers, Oct 29 2006

Status

approved