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

1, 6, 23, 94, 380, 1494, 5939, 23398, 92317, 363370, 1430190, 5625584, 22124617, 86997410, 342060007, 1344843036, 5287206382, 20786010360, 81716574499, 321251714484, 1262927656331, 4964894997840, 19518245673568, 76731015101962

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