A220529 Equals two maps: number of nX2 binary arrays indicating the locations of corresponding elements equal to exactly two of their horizontal, vertical and antidiagonal neighbors in a random 0..3 nX2 array

1, 6, 27, 107, 461, 1844, 7502, 29893, 119342, 473933, 1881751, 7461042, 29575992, 117195951, 464344817, 1839594735, 7287640647, 28869446541, 114362678138, 453029324891, 1794595194945, 7108951540013, 28160738630498, 111553241825416

Offset

1,2

Comments

Column 2 of A220532

Links

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

Formula

Empirical: a(n) = 6*a(n-1) -5*a(n-2) -18*a(n-3) +24*a(n-4) -3*a(n-5) +a(n-6) -49*a(n-7) +113*a(n-8) +136*a(n-9) -407*a(n-10) +376*a(n-11) +261*a(n-12) -819*a(n-13) -157*a(n-14) +1276*a(n-15) -1095*a(n-16) -1063*a(n-17) +566*a(n-18) +423*a(n-19) -11368*a(n-20) +9391*a(n-21) -15574*a(n-22) -8963*a(n-23) +1529*a(n-24) -27108*a(n-25) +1001*a(n-26) -32699*a(n-27) -41186*a(n-28) +30586*a(n-29) -143578*a(n-30) +53047*a(n-31) -116139*a(n-32) +389*a(n-33) -37253*a(n-34) -146288*a(n-35) +52769*a(n-36) -111475*a(n-37) -122524*a(n-38) +42899*a(n-39) -163248*a(n-40) +149127*a(n-41) -118651*a(n-42) -49351*a(n-43) +76302*a(n-44) -57124*a(n-45) -7405*a(n-46) +26959*a(n-47) -45252*a(n-48) +27865*a(n-49) -8493*a(n-50) -2541*a(n-51) +10641*a(n-52) -4206*a(n-53) -595*a(n-54) +3901*a(n-55) -2258*a(n-56) +316*a(n-57) +784*a(n-58) -793*a(n-59) +318*a(n-60) -22*a(n-61) -63*a(n-62) +41*a(n-63) -18*a(n-64) +a(n-65)

Example

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

Crossrefs

Sequence in context: A005325 A099623 A119852 * A027471 A305780 A037695

Adjacent sequences: A220526 A220527 A220528 * A220530 A220531 A220532

Keyword

nonn

Author

R. H. Hardin Dec 15 2012

Status

approved