OFFSET
0,3
COMMENTS
Toothpicks are connected by their endpoints. The toothpicks placed in north direction are prohibited. The sequence gives the number of toothpicks after n-th stage in the structure. A233971 (the first differences) give the number of toothpicks added at n-th stage.
First differs from A169780 at a(24).
LINKS
CROSSREFS
KEYWORD
nonn
AUTHOR
Omar E. Pol, Dec 18 2013
STATUS
approved