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A191604 Number of n X n symmetric binary matrices with each 1 adjacent to no more than 5 horizontally, vertically or diagonally neighboring 1s 1
2, 8, 62, 966, 29888, 1838552, 224969616, 54745613520, 26495136860880, 25502057625872912, 48817512227401500592, 185852155121293444267024, 1407184656492293192061559200, 21189763355834331020518358995456 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..21

EXAMPLE

Some solutions for n=4

..0..0..1..1....1..1..1..1....1..1..1..1....1..0..0..0....1..0..1..1

..0..1..0..1....1..1..1..0....1..0..1..1....0..1..1..1....0..0..1..1

..1..0..0..0....1..1..0..1....1..1..1..0....0..1..0..1....1..1..0..0

..1..1..0..1....1..0..1..0....1..1..0..1....0..1..1..1....1..1..0..1

CROSSREFS

Sequence in context: A006245 A202751 A227160 * A009271 A153539 A153567

Adjacent sequences:  A191601 A191602 A191603 * A191605 A191606 A191607

KEYWORD

nonn

AUTHOR

R. H. Hardin Jun 08 2011

STATUS

approved

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Last modified November 13 20:57 EST 2019. Contains 329106 sequences. (Running on oeis4.)