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A181259
Number of (n+2)X7 binary matrices with every 3X3 block having exactly four 1's
2
7218, 10348, 14974, 22512, 41374, 79324, 162882, 387076, 952462, 2438184, 6643798, 18382036, 51676218, 148824748, 431409094, 1258929552, 3710111854, 10965458044, 32503791762, 96750343636, 288356652382, 860533686264, 2572693730758
OFFSET
1,1
COMMENTS
Column 5 of A181262
LINKS
FORMULA
Empirical: a(n)=6*a(n-1)-11*a(n-2)+42*a(n-3)-216*a(n-4)+396*a(n-5)-719*a(n-6)+3018*a(n-7)-5533*a(n-8)+6498*a(n-9)-20880*a(n-10)+38280*a(n-11)-33444*a(n-12)+75384*a(n-13)-138204*a(n-14)+97848*a(n-15)-134784*a(n-16)+247104*a(n-17)-150336*a(n-18)+93312*a(n-19)-171072*a(n-20)+93312*a(n-21)
EXAMPLE
Some solutions for 4X7
..0..0..1..1..0..1..0....1..0..0..1..0..0..1....0..1..1..0..1..0..0
..0..0..0..0..1..0..1....0..0..1..0..0..1..1....1..0..0..1..0..1..1
..1..1..1..0..0..1..0....1..1..0..1..1..0..0....0..0..1..0..0..1..0
..0..1..0..1..1..0..0....0..1..0..0..1..0..0....1..0..1..1..0..0..1
CROSSREFS
Sequence in context: A239566 A236993 A218513 * A250054 A346594 A202402
KEYWORD
nonn
AUTHOR
R. H. Hardin Oct 10 2010
STATUS
approved