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A268770 Number of n X 4 0..2 arrays with some element plus some horizontally, vertically, diagonally or antidiagonally adjacent neighbor totalling two exactly once. 1
36, 100, 446, 2296, 10340, 46312, 198114, 837848, 3472210, 14245712, 57796288, 232692368, 930069146, 3696103032, 14612457534, 57516087912, 225502135332, 881077245816, 3431904293122, 13330760323672, 51652205043266 (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) = 4*a(n-1) + 10*a(n-2) - 32*a(n-3) - 47*a(n-4) + 40*a(n-5) + 38*a(n-6) - 12*a(n-7) - 9*a(n-8) for n>10.

Empirical g.f.: 2*x*(18 - 22*x - 157*x^2 + 332*x^3 + 794*x^4 - 238*x^5 - 734*x^6 - 72*x^7 + 189*x^8 + 54*x^9) / (1 - 2*x - 7*x^2 + 2*x^3 + 3*x^4)^2. - Colin Barker, Jan 15 2019

EXAMPLE

Some solutions for n=4:

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

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

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

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

CROSSREFS

Column 4 of A268774.

Sequence in context: A085986 A027603 A250813 * A323064 A163246 A014738

Adjacent sequences:  A268767 A268768 A268769 * A268771 A268772 A268773

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 13 2016

STATUS

approved

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Last modified January 25 16:42 EST 2020. Contains 331245 sequences. (Running on oeis4.)