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
Keywords
Examples
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
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)
Comments