OFFSET
0,3
COMMENTS
A subset of the arrangements of n circles described in A250001.
Note that a(4) = 155 does not include the arrangement of four circles in which there is a little circle that is surrounded by the union of three solid circles, because in that arrangement there are two islands or regions, not one.
CROSSREFS
KEYWORD
nonn,hard,more
AUTHOR
Omar E. Pol, May 21 2017
STATUS
approved