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

1,2

Comments

Row 2 of A220935

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)

Example

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

Crossrefs

Sequence in context: A336994 A107767 A319775 * A232399 A223711 A074409

Adjacent sequences: A220933 A220934 A220935 * A220937 A220938 A220939

Keyword

nonn

Author

R. H. Hardin Dec 25 2012

Status

approved