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A302323 Number of 2Xn 0..1 arrays with every element equal to 0, 1, 2 or 4 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero. 4
2, 8, 20, 52, 136, 360, 960, 2576, 6944, 18784, 50944, 138432, 376704, 1026176, 2797568, 7631104, 20824576, 56845824, 155209728, 423848960, 1157593088, 3161835520, 8636760064, 23592996864, 64451125248, 176071467008, 481011630080 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 2 of A302322.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

FORMULA

Empirical: a(n) = 4*a(n-1) -2*a(n-2) -4*a(n-3) for n>4

EXAMPLE

Some solutions for n=5

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

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

CROSSREFS

Cf. A302322.

Sequence in context: A058405 A133326 A285185 * A192698 A305050 A279898

Adjacent sequences:  A302320 A302321 A302322 * A302324 A302325 A302326

KEYWORD

nonn

AUTHOR

R. H. Hardin, Apr 05 2018

STATUS

approved

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Last modified November 30 05:46 EST 2021. Contains 349419 sequences. (Running on oeis4.)