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A207170 Number of 2Xn 0..1 arrays avoiding 0 0 0 and 1 0 1 horizontally and 0 0 1 and 1 0 1 vertically 18
4, 16, 36, 81, 169, 361, 784, 1681, 3600, 7744, 16641, 35721, 76729, 164836, 354025, 760384, 1633284, 3508129, 7535025, 16184529, 34762816, 74666881, 160376896, 344473600, 739894401, 1589218225, 3413480625, 7331811876, 15747991081 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 2 of A207169

LINKS

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

FORMULA

Empirical: a(n) = a(n-1) +a(n-2) +3*a(n-3) +a(n-4) -a(n-5) -a(n-6) for n>7

G.f: 4*x -x^2*(-16-20*x-29*x^2-4*x^3+13*x^4+9*x^5) / ( (x^3+2*x^2+x-1)*(x^3-x^2-1) ). - R. J. Mathar, Aug 10 2017

Empirical: 31*a(n) = 114*A002478(n) +133*A002478(n-1) +55*A002478(n) +10*A077961(n) +32*A077961(n-1) -24*A077961(n-2) for n>1. - R. J. Mathar, Nov 09 2018

EXAMPLE

Some solutions for n=4

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

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

CROSSREFS

Sequence in context: A085040 A030179 A207025 * A207069 A207436 A189145

Adjacent sequences: A207167 A207168 A207169 * A207171 A207172 A207173

KEYWORD

nonn

AUTHOR

R. H. Hardin Feb 15 2012

STATUS

approved

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Last modified December 3 11:24 EST 2022. Contains 358517 sequences. (Running on oeis4.)