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A123792 Number of ways to build a contiguous building with n LEGO blocks of size 1 X 5 on top of a fixed block of the same size so that the building is flat, i.e., with all blocks in parallel position. 0
9, 91, 1089, 13726, 182736, 2493062, 34865595, 495114895, 7127585291 (list; graph; refs; listen; history; text; internal format)
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..9.

CROSSREFS

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

Sequence in context: A335508 A176735 A286786 * A022520 A020236 A068624

Adjacent sequences:  A123789 A123790 A123791 * A123793 A123794 A123795

KEYWORD

nonn,hard

AUTHOR

Søren Eilers, Oct 29 2006

STATUS

approved

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Last modified September 20 17:16 EDT 2020. Contains 337265 sequences. (Running on oeis4.)