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A198709 Number of n X n 0..3 arrays with values 0..3 introduced in row major order and no element equal to any horizontal or vertical neighbor 2
1, 4, 401, 250031, 851787199, 15835552812749, 1606578861528554441, 889483369334451647489771, 2687450673445984030296455830409 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Diagonal of A198715

LINKS

Jean-François Alcover, Table of n, a(n) for n = 1..16

EXAMPLE

Some solutions with all values from 0 to 3 for n=4

..0..1..0..1....0..1..0..2....0..1..0..1....0..1..0..2....0..1..2..0

..1..2..1..3....1..2..1..3....1..0..2..3....2..3..2..3....1..0..3..1

..2..1..3..2....2..1..3..2....2..3..1..2....1..2..0..1....0..3..1..2

..1..3..1..0....1..2..0..1....3..0..2..1....2..0..3..0....2..1..2..3

MATHEMATICA

A198715 = Import["https://oeis.org/A198715/b198715.txt", "Table"][[All, 2]];

a[n_] := A198715[[2 n^2 - 2 n + 1]];

Table[a[n], {n, 1, 16}] (* Jean-François Alcover, Sep 23 2019 *)

CROSSREFS

Sequence in context: A158111 A259049 A280791 * A326209 A287965 A215647

Adjacent sequences:  A198706 A198707 A198708 * A198710 A198711 A198712

KEYWORD

nonn

AUTHOR

R. H. Hardin Oct 29 2011

STATUS

approved

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Last modified June 13 06:38 EDT 2021. Contains 344981 sequences. (Running on oeis4.)