A191224 - OEIS

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A191224

Number of n X n symmetric binary matrices with each 1 adjacent to exactly 3 king-move neighboring 1s

1, 2, 3, 4, 10, 29, 74, 267, 1270, 6853, 46338, 452697, 5888876, 103743236, 2568916974, 83100685126, 3548166614885, 196909507948313, 14058252177537760

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

OFFSET

1,2

LINKS

Table of n, a(n) for n=1..19.

EXAMPLE

All solutions for n=4

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

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

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

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

CROSSREFS

Sequence in context: A123700 A005433 A139009 * A359995 A272523 A337536

Adjacent sequences: A191221 A191222 A191223 * A191225 A191226 A191227

KEYWORD

nonn

AUTHOR

R. H. Hardin May 27 2011

STATUS

approved