

A165764


Smallest size of which there are n tatamifree rooms.


2



70, 198, 336, 504, 1320, 1440, 3696, 3360, 5040, 8400, 6720, 10080, 16632, 16800, 18480, 20160, 15120, 33264, 37800, 30240, 45360, 73920, 60480, 65520, 85680, 55440, 124740, 142560, 138600, 151200, 131040, 180180, 257040, 110880, 166320
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OFFSET

1,1


COMMENTS

A tatamifree room is a rectangle of even size that allows no 1x2 domino tiling satisfying the tatami rule, i.e. such that there is no point in which 4 tiles meet.


LINKS



FORMULA



EXAMPLE

The smallest tatamifree room is of size 7x10, and all other rectangles of this size allow for a tatami tiling, thus a(1) = 70.
a(5)=1320 is the smallest size of which there are exactly 5 tatamifree rooms, namely 20x66, 22x60, 24x55, 30x44 and 33x40.


CROSSREFS



KEYWORD

nonn


AUTHOR



STATUS

approved



