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A220372 Equals two maps: number of nX2 binary arrays indicating the locations of corresponding elements equal to exactly two of their horizontal and vertical neighbors in a random 0..2 nX2 array 4
1, 6, 23, 94, 380, 1494, 5939, 23398, 92317, 363370, 1430190, 5625584, 22124617, 86997410, 342060007, 1344843036, 5287206382, 20786010360, 81716574499, 321251714484, 1262927656331, 4964894997840, 19518245673568, 76731015101962 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Column 2 of A220375

LINKS

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

FORMULA

Empirical: a(n) = 8*a(n-1) -21*a(n-2) +23*a(n-3) -17*a(n-4) +11*a(n-5) +55*a(n-6) -199*a(n-7) +241*a(n-8) -157*a(n-9) -14*a(n-10) +217*a(n-11) -546*a(n-12) +850*a(n-13) -927*a(n-14) +254*a(n-15) +555*a(n-16) -375*a(n-17) +150*a(n-18) +848*a(n-19) +368*a(n-20) +998*a(n-21) +666*a(n-22) +1091*a(n-23) +2744*a(n-24) +1499*a(n-25) +3393*a(n-26) +1420*a(n-27) +3704*a(n-28) -272*a(n-29) +3190*a(n-30) -1290*a(n-31) +1774*a(n-32) -418*a(n-33) +486*a(n-34) -72*a(n-35) +68*a(n-36) -8*a(n-37)

EXAMPLE

Some solutions for n=3

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

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

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

CROSSREFS

Sequence in context: A013265 A228703 A344815 * A321715 A038383 A120775

Adjacent sequences:  A220369 A220370 A220371 * A220373 A220374 A220375

KEYWORD

nonn

AUTHOR

R. H. Hardin Dec 13 2012

STATUS

approved

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Last modified January 26 06:41 EST 2022. Contains 350572 sequences. (Running on oeis4.)