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A297432 Number of 2 X n 0..1 arrays with every 1 horizontally, diagonally or antidiagonally adjacent to 2 neighboring 1s. 1
1, 2, 7, 12, 18, 33, 73, 139, 244, 449, 880, 1680, 3105, 5781, 10981, 20806, 39007, 73112, 137842, 260073, 489213, 919503, 1730944, 3260449, 6136804, 11545760, 21729985, 40908585, 77001561, 144914586, 272743111, 513379012, 966299842 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

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

FORMULA

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

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

EXAMPLE

Some solutions for n=5:

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

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

CROSSREFS

Row 2 of A297431.

Sequence in context: A220120 A131190 A099353 * A299401 A188039 A133459

Adjacent sequences:  A297429 A297430 A297431 * A297433 A297434 A297435

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 30 2017

STATUS

approved

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Last modified May 17 22:15 EDT 2021. Contains 343992 sequences. (Running on oeis4.)