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A251187 Number of (n+2)X(1+2) 0..1 arrays with nondecreasing sum of every three consecutive values in every row and column 1
512, 1728, 5832, 19683, 46656, 110592, 262144, 512000, 1000000, 1953125, 3375000, 5832000, 10077696, 16003008, 25412184, 40353607, 60236288, 89915392, 134217728, 191102976, 272097792, 387420489, 531441000, 729000000, 1000000000, 1331000000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 1 of A251192

LINKS

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

FORMULA

Empirical: a(n) = 2*a(n-1) -a(n-2) +8*a(n-3) -16*a(n-4) +8*a(n-5) -28*a(n-6) +56*a(n-7) -28*a(n-8) +56*a(n-9) -112*a(n-10) +56*a(n-11) -70*a(n-12) +140*a(n-13) -70*a(n-14) +56*a(n-15) -112*a(n-16) +56*a(n-17) -28*a(n-18) +56*a(n-19) -28*a(n-20) +8*a(n-21) -16*a(n-22) +8*a(n-23) -a(n-24) +2*a(n-25) -a(n-26)

Empirical for n mod 3 = 0: a(n) = (1/19683)*n^9 + (5/2187)*n^8 + (11/243)*n^7 + (377/729)*n^6 + (304/81)*n^5 + (484/27)*n^4 + (1520/27)*n^3 + 112*n^2 + 128*n + 64

Empirical for n mod 3 = 1: a(n) = (1/19683)*n^9 + (5/2187)*n^8 + (100/2187)*n^7 + (3500/6561)*n^6 + (8750/2187)*n^5 + (43750/2187)*n^4 + (437500/6561)*n^3 + (312500/2187)*n^2 + (390625/2187)*n + (1953125/19683)

Empirical for n mod 3 = 2: a(n) = (1/19683)*n^9 + (5/2187)*n^8 + (11/243)*n^7 + (3397/6561)*n^6 + (8248/2187)*n^5 + (13232/729)*n^4 + (378880/6561)*n^3 + (256256/2187)*n^2 + (100352/729)*n + (1404928/19683)

EXAMPLE

Some solutions for n=6

..0..0..0....0..0..0....0..0..0....1..0..0....0..0..0....0..0..0....1..0..0

..0..0..0....0..0..1....0..1..1....0..1..0....0..0..0....1..1..0....1..0..0

..1..0..1....0..1..0....0..1..1....0..0..0....1..0..0....0..1..1....1..0..1

..1..0..0....0..1..1....1..1..1....1..0..0....0..0..1....0..0..0....1..0..0

..1..0..1....0..0..1....1..1..1....0..1..1....0..1..0....1..1..0....1..0..0

..1..0..1....0..1..0....0..1..1....0..0..0....1..0..0....0..1..1....1..0..1

..1..1..0....0..1..1....1..1..1....1..1..0....1..1..1....0..0..1....1..1..1

..1..0..1....1..1..1....1..1..1....0..1..1....0..1..1....1..1..0....1..1..1

CROSSREFS

Sequence in context: A235192 A203451 A251192 * A223333 A135273 A258522

Adjacent sequences:  A251184 A251185 A251186 * A251188 A251189 A251190

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 30 2014

STATUS

approved

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Last modified June 19 19:11 EDT 2019. Contains 324222 sequences. (Running on oeis4.)