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A235510 Number of (n+1) X (1+1) 0..1 arrays with the sum of each 2 X 2 subblock maximum and minimum lexicographically nondecreasing rowwise and columnwise. 2
16, 58, 209, 746, 2660, 9476, 33753, 120216, 428160, 1524918, 5431081, 19343086, 68891428, 245360464, 873864257, 3112313708, 11084669648, 39478636370, 140605248417, 500773018002, 1783529550852, 6352134688572, 22623463167433 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 1 of A235517.

LINKS

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

FORMULA

Empirical: a(n) = 4*a(n-1) - 6*a(n-3) + a(n-4) + 2*a(n-5).

Conjectures from Colin Barker, Mar 19 2018: (Start)

G.f.: x*(16 - 6*x - 23*x^2 + 6*x^3 + 8*x^4) / ((1 - x)^2*(1 + x)*(1 - 3*x - 2*x^2)).

a(n) = (1/544)*(-221 - 68*(-1)^n + 2^(-1-n)*((2533-611*sqrt(17))*(3-sqrt(17))^n + (3+sqrt(17))^n*(2533+611*sqrt(17))) - 68*(1+n)).

(End)

EXAMPLE

Some solutions for n=4:

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

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

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

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

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

CROSSREFS

Cf. A235517.

Sequence in context: A005905 A177890 A225922 * A220974 A063521 A027117

Adjacent sequences:  A235507 A235508 A235509 * A235511 A235512 A235513

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 11 2014

STATUS

approved

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Last modified November 29 21:32 EST 2021. Contains 349416 sequences. (Running on oeis4.)