A145810 Number of islands of ones fitting in an n X n array symmetric under horizontal reflection with all ones connected only either three adjacent vertically or three adjacent horizontally.

0, 0, 2, 2, 4, 4, 8, 8, 14, 12, 20, 20, 27, 28, 38, 36, 47, 48

Offset

1,3

Links

Table of n, a(n) for n=1..18.

Example

8 X 8 example with 8 islands
.1.1.1.0.0.1.1.1
.0.0.0.0.0.0.0.0
.0.0.0.0.0.0.0.0
.1.1.1.0.0.1.1.1
.0.0.0.0.0.0.0.0
.1.0.1.0.0.1.0.1
.1.0.1.0.0.1.0.1
.1.0.1.0.0.1.0.1

Crossrefs

Sequence in context: A108747 A116931 A206558 * A172148 A205478 A262966

Adjacent sequences: A145807 A145808 A145809 * A145811 A145812 A145813

Keyword

nonn

Author

R. H. Hardin, Oct 20 2008

Status

approved