A145802 - OEIS

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A145802

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

0, 1, 2, 4, 6, 9, 12, 15, 19, 25, 28, 33, 40, 49, 53, 60, 69, 81, 86, 95

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,3

LINKS

Table of n, a(n) for n=1..20.

EXAMPLE

8 X 8 example with 15 islands

.1.0.0.1.1.0.0.1

.1.0.1.0.0.1.0.1

.0.0.1.0.0.1.0.0

.1.1.0.1.1.0.1.1

.0.0.1.0.0.1.0.0

.1.0.1.0.0.1.0.1

.1.0.0.1.1.0.0.1

.0.1.1.0.0.1.1.0

CROSSREFS

Sequence in context: A261222 A130025 A278299 * A076271 A036441 A180107

Adjacent sequences: A145799 A145800 A145801 * A145803 A145804 A145805

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 19 2008

STATUS

approved