0,2

F. Ardila and R. P. Stanley, Tilings

Jim McCann, Triangle Sequence

N. C. Saldanha and C. Tomei, [math/9801111] An overview of domino and lozenge tilings

Torsten Sillke, A Word Problem

n is in the sequence iff n == 0, 2, 9, or 11 (mod 12). See Sillke link. - Sascha Kurz (sascha.kurz(AT)uni-bayreuth.de), Mar 04 2003

A possible side-9 arrangement:

....... A

...... A A

..... B B C

.... D B C C

... D D E E F

.. G H H E F F

. G G H I I J J

.K L L M I N J O

K K L M M N N O O

Sequence in context: A073082 A006172 A085069 this_sequence A137000 A073634 A065554

Adjacent sequences: A072062 A072063 A072064 this_sequence A072066 A072067 A072068

nonn,nice

Jim McCann (jmccann(AT)umich.edu), Aug 04 2002