A221663 Sum of neighbor maps: number of nX2 binary arrays indicating the locations of corresponding elements equal to the sum mod 3 of their horizontal, diagonal and antidiagonal neighbors in a random 0..2 nX2 array

2, 12, 48, 256, 856, 4096, 15872, 65344, 259584, 1048576, 4177632, 16777216, 67051520, 268430336, 1073479680, 4294967296, 17178580480, 68719476736, 274872664064, 1099511513088, 4398023442432, 17592186044416, 70368641459200

Offset

1,1

Comments

Column 2 of A221666

Links

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

Formula

Empirical: a(n) = 4*a(n-1) +8*a(n-2) -32*a(n-3) -16*a(n-4) +64*a(n-5) +52*a(n-6) -208*a(n-7) -416*a(n-8) +1664*a(n-9) +832*a(n-10) -3328*a(n-11) -1056*a(n-12) +4224*a(n-13) +8448*a(n-14) -33792*a(n-15) -16896*a(n-16) +67584*a(n-17) +10880*a(n-18) -43520*a(n-19) -87040*a(n-20) +348160*a(n-21) +174080*a(n-22) -696320*a(n-23) -62720*a(n-24) +250880*a(n-25) +501760*a(n-26) -2007040*a(n-27) -1003520*a(n-28) +4014080*a(n-29) +205824*a(n-30) -823296*a(n-31) -1646592*a(n-32) +6586368*a(n-33) +3293184*a(n-34) -13172736*a(n-35) -360448*a(n-36) +1441792*a(n-37) +2883584*a(n-38) -11534336*a(n-39) -5767168*a(n-40) +23068672*a(n-41) +262144*a(n-42) -1048576*a(n-43) -2097152*a(n-44) +8388608*a(n-45) +4194304*a(n-46) -16777216*a(n-47)

Example

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

Crossrefs

Sequence in context: A354131 A370696 A052569 * A232663 A052591 A029766

Adjacent sequences: A221660 A221661 A221662 * A221664 A221665 A221666

Keyword

nonn

Author

R. H. Hardin Jan 21 2013

Status

approved