OFFSET
0,4
COMMENTS
The envelope of a polyomino is the minimal rectangle containing it.
EXAMPLE
a(3) = 2;
The two possible envelopes are
|*|
|*|
|*| area = 3;
and
|*| |
|*|*| area = 4.
CROSSREFS
KEYWORD
nonn
AUTHOR
Francois Alcover, Feb 28 2017
STATUS
approved
