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A193808 Number of n X n symmetric 0..3 arrays with no element equal to the difference mod 4 of any two of its horizontal and vertical neighbors 1
4, 23, 133, 1465, 37741, 2194501, 271424321, 68861945361, 35194944674859, 36030017205738273, 73787195288621907455, 302231516037239516908817, 2475880105112954130388596401, 40564819225226093549492737413585 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

EXAMPLE

Some solutions for 4X4

..3..3..3..1....1..1..1..3....3..3..1..1....1..1..1..1....1..2..1..2

..3..3..1..1....1..3..1..1....3..3..3..3....1..3..3..1....2..1..2..1

..3..1..3..1....1..1..3..3....1..3..1..1....1..3..3..3....1..2..1..2

..1..1..1..1....3..1..3..3....1..3..1..3....1..1..3..3....2..1..2..1

CROSSREFS

Sequence in context: A227639 A291026 A239399 * A038723 A302761 A091640

Adjacent sequences:  A193805 A193806 A193807 * A193809 A193810 A193811

KEYWORD

nonn

AUTHOR

R. H. Hardin Aug 05 2011

STATUS

approved

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Last modified May 7 16:00 EDT 2021. Contains 343652 sequences. (Running on oeis4.)