A220936 Equals two maps: number of 2Xn binary arrays indicating the locations of corresponding elements equal to exactly two of their horizontal and antidiagonal neighbors in a random 0..2 2Xn array.

1, 4, 16, 52, 200, 792, 3080, 12164, 47827, 188078, 739654, 2908308, 11433623, 44951623, 176719636, 694738324, 2731215010, 10737125607, 42210368413, 165939449883, 652348443363, 2564539277676, 10081819289214, 39634040551712

Offset: 1

Author

R. H. Hardin Dec 25 2012

Keywords

• nonn

Comments

Row 2 of A220935

Examples

			Some solutions for n=3
..0..0..1....0..0..0....0..1..0....0..1..0....0..0..1....0..0..1....0..1..1
..0..0..0....1..0..0....1..1..0....1..0..0....0..1..0....1..1..0....1..0..0
		

Links

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

Formula

Empirical: a(n) = 8*a(n-1) -22*a(n-2) +36*a(n-3) -83*a(n-4) +180*a(n-5) -202*a(n-6) +134*a(n-7) -163*a(n-8) -148*a(n-9) +1102*a(n-10) -1964*a(n-11) +2361*a(n-12) -2806*a(n-13) +1954*a(n-14) +698*a(n-15) -6089*a(n-16) +12746*a(n-17) -16274*a(n-18) +16250*a(n-19) -15958*a(n-20) +11458*a(n-21) +1206*a(n-22) -9876*a(n-23) +17244*a(n-24) -3208*a(n-25) +14772*a(n-26) -4156*a(n-27) +26925*a(n-28) +6308*a(n-29) +50808*a(n-30) +12984*a(n-31) +97889*a(n-32) +17770*a(n-33) +128262*a(n-34) +38432*a(n-35) +149644*a(n-36) +109876*a(n-37) +157919*a(n-38) +178940*a(n-39) +130160*a(n-40) +199080*a(n-41) +94482*a(n-42) +171386*a(n-43) +61079*a(n-44) +118320*a(n-45) +49065*a(n-46) +54958*a(n-47) +32068*a(n-48) +15960*a(n-49) +13770*a(n-50) +6182*a(n-51) +4376*a(n-52) +1600*a(n-53) +766*a(n-54) +188*a(n-55) +28*a(n-56) -8*a(n-57)