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A235897
Number of (n+1) X (3+1) 0..2 arrays with the minimum plus the maximum equal to the lower median plus the upper median in every 2 X 2 subblock.
1
473, 3265, 21697, 148945, 1030145, 7234417, 51386977, 369219409, 2679887681, 19633204273, 145044113953, 1079669229841, 8091619731713, 61015969790449, 462652793596897, 3525659262889681, 26989485570486977, 207460867269846961
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = 21*a(n-1) - 124*a(n-2) - 72*a(n-3) + 2128*a(n-4) - 432*a(n-5) - 12608*a(n-6) - 10752*a(n-7).
Empirical g.f.: x*(473 - 6668*x + 11784*x^2 + 132224*x^3 - 178736*x^4 - 1110848*x^5 - 870912*x^6) / ((1 + 2*x)*(1 - 6*x)*(1 - 8*x)*(1 - 6*x - 8*x^2)*(1 - 3*x - 14*x^2)). - Colin Barker, Oct 20 2018
EXAMPLE
Some solutions for n=4:
..0..1..2..0....1..2..1..1....0..2..1..0....1..0..2..2....1..1..0..1
..0..1..2..0....2..1..0..0....1..1..2..1....2..1..1..1....0..2..1..2
..2..1..0..2....2..1..0..0....2..0..1..2....1..2..2..2....0..2..1..0
..1..2..1..1....0..1..0..0....0..2..1..0....2..1..1..1....1..1..0..1
..2..1..0..2....1..0..1..1....1..1..0..1....1..2..0..0....2..2..1..0
CROSSREFS
Column 3 of A235902.
Sequence in context: A157434 A084629 A075286 * A215738 A348806 A370295
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 16 2014
STATUS
approved