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A123825 Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 2x3 which is symmetric after a rotation by 180 degrees. 0
1, 1, 25, 53, 1189, 2947, 66094, 181955, 3979943 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

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

CROSSREFS

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

Sequence in context: A118304 A117472 A146633 * A157269 A186892 A206075

Adjacent sequences:  A123822 A123823 A123824 * A123826 A123827 A123828

KEYWORD

nonn

AUTHOR

Søren Eilers, Oct 29 2006

STATUS

approved

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Last modified June 13 05:41 EDT 2021. Contains 344981 sequences. (Running on oeis4.)