A123826 Number of ways to build a contiguous building with n LEGO blocks of size 2x3 on top of a fixed block of the same size.

31, 1165, 57415, 3060464, 176633912, 10625603236, 661642082820

Offset

1,1

Comments

The base block is not counted among the n and must be the only block in the bottom layer of the building

Links

Table of n, a(n) for n=1..7.

Crossrefs

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

Sequence in context: A138861 A015257 A199234 * A130004 A182784 A139162

Adjacent sequences: A123823 A123824 A123825 * A123827 A123828 A123829

Keyword

nonn,hard

Author

Søren Eilers, Oct 29 2006

Status

approved