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A123839 Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 4 X 4 which is symmetric after a rotation by 180 degrees. 0
1, 1, 21, 67, 1565, 6241, 137613, 630193, 13136926 (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: A219379 A168240 A123779 * A180758 A197121 A175461

Adjacent sequences:  A123836 A123837 A123838 * A123840 A123841 A123842

KEYWORD

nonn

AUTHOR

Søren Eilers, Oct 29 2006

STATUS

approved

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Last modified October 5 06:51 EDT 2022. Contains 357252 sequences. (Running on oeis4.)