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A297458 Number of 2 X n 0..1 arrays with every 1 horizontally, diagonally or antidiagonally adjacent to 0 or 2 neighboring 1s. 1
4, 8, 25, 57, 156, 384, 1009, 2545, 6580, 16760, 43081, 110121, 282444, 722928, 1852705, 4744417, 12155236, 31132904, 79753849, 204285465, 523300860, 1340442720, 3433646161, 8795417041, 22530001684, 57711669848, 147831676585 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

FORMULA

Empirical: a(n) = a(n-1) + 3*a(n-2) + a(n-3) + 4*a(n-4).

Empirical g.f.: x*(4 + 4*x + 5*x^2 + 4*x^3) / ((1 + x^2)*(1 - x - 4*x^2)). - Colin Barker, Feb 28 2019

EXAMPLE

Some solutions for n=7:

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

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

CROSSREFS

Row 2 of A297457.

Sequence in context: A068367 A292548 A000964 * A328038 A107840 A046736

Adjacent sequences:  A297455 A297456 A297457 * A297459 A297460 A297461

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 30 2017

STATUS

approved

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Last modified August 12 08:33 EDT 2020. Contains 336438 sequences. (Running on oeis4.)