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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. 0
1, 7, 109, 1877, 35243, 685817, 13719483, 279714347, 5788634457 (list; graph; refs; listen; history; text; internal format)
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 * A274668 A239848 A274787

Adjacent sequences:  A123801 A123802 A123803 * A123805 A123806 A123807

KEYWORD

nonn,hard

AUTHOR

Søren Eilers, Oct 29 2006

STATUS

approved

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Last modified November 21 12:11 EST 2019. Contains 329370 sequences. (Running on oeis4.)