A235549 - OEIS

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A235549

Number of (n+1) X (1+1) 0..1 arrays with the sum of each 2 X 2 subblock two extreme terms minus its two median terms lexicographically nondecreasing rowwise and columnwise.

16, 46, 120, 288, 660, 1456, 3136, 6624, 13808, 28480, 58304, 118656, 240448, 485632, 978432, 1967616, 3951360, 7926784, 15889408, 31832064, 63742976, 127602688, 255377408, 511008768, 1022390272, 2045329408, 4091461632, 8184102912

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

Column 1 of A235555.

LINKS

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

FORMULA

Empirical: a(n) = 2*a(n-1) + 4*a(n-2) - 8*a(n-3) - 4*a(n-4) + 8*a(n-5).

Empirical g.f.: 2*x*(8 + 7*x - 18*x^2 - 4*x^3 + 18*x^4) / ((1 - 2*x)*(1 - 2*x^2)^2). - Colin Barker, Mar 19 2018

EXAMPLE

Some solutions for n=5:

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

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

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

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

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

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

CROSSREFS

Cf. A235555.

Sequence in context: A099003 A124709 A244094 * A126370 A133345 A253231

Adjacent sequences: A235546 A235547 A235548 * A235550 A235551 A235552

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 12 2014

STATUS

approved