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A227267
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Number of nX4 0,1 arrays indicating 2X2 subblocks of some larger (n+1)X5 binary array having a sum of three or less, with rows and columns of the latter in lexicographically nondecreasing order
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1
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5, 30, 132, 513, 1949, 7131, 24496, 78761, 238146, 681095, 1852355, 4813290, 11999195, 28801351, 66769946, 149914163, 326768708, 692941231, 1432287640, 2890510485, 5704099317, 11022017108, 20880164204, 38823463828, 70923212058
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OFFSET
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1,1
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COMMENTS
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LINKS
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FORMULA
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Empirical: a(n) = (1/121645100408832000)*n^19 + (1/6402373705728000)*n^18 + (23/1067062284288000)*n^17 + (31/62768369664000)*n^16 + (37/5706215424000)*n^15 + (4111/5706215424000)*n^14 - (301079/47076277248000)*n^13 + (126941/452656512000)*n^12 + (14792293/9656672256000)*n^11 - (78942259/877879296000)*n^10 + (13084929349/4828336128000)*n^9 - (165214115519/4828336128000)*n^8 + (5087156753417/23538138624000)*n^7 + (3282017247319/2942267328000)*n^6 - (4087118559803/118879488000)*n^5 + (37821361216913/118879488000)*n^4 - (460675235565641/308756448000)*n^3 + (19317471160409/6175128960)*n^2 + (109108917509/232792560)*n - 9102 for n>7
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EXAMPLE
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Some solutions for n=4
..1..1..1..1....1..1..1..0....1..1..1..1....1..1..1..1....1..1..1..0
..1..1..1..0....1..1..1..1....1..1..1..1....1..1..0..0....1..1..0..0
..1..0..1..1....0..1..1..1....1..1..0..1....1..0..0..0....1..1..0..0
..0..0..1..1....0..1..1..0....1..1..1..1....1..1..1..1....1..0..0..0
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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