A145801 Number of islands of ones fitting in an n X n array with all ones connected only either two adjacent vertically or two adjacent horizontally.

0, 1, 2, 4, 6, 9, 12, 16, 19, 25, 29, 36

Offset

1,3

Links

Table of n, a(n) for n=1..12.

Example

8 X 8 example with 16 islands
.0.1.0.1.0.1.0.1
.0.1.0.1.0.1.0.1
.1.0.1.0.1.0.1.0
.1.0.1.0.1.0.1.0
.0.1.0.1.0.1.0.1
.0.1.0.1.0.1.0.1
.1.0.1.0.1.0.0.0
.1.0.1.0.1.0.1.1

Crossrefs

Sequence in context: A258027 A053096 A155752 * A033291 A105434 A145196

Adjacent sequences: A145798 A145799 A145800 * A145802 A145803 A145804

Keyword

nonn

Author

R. H. Hardin, Oct 19 2008

Status

approved