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A183983 1/4 the number of (n+1) X 7 binary arrays with all 2 X 2 subblock sums the same. 1
45, 47, 50, 56, 66, 86, 122, 194, 330, 602, 1130, 2186, 4266, 8426, 16682, 33194, 66090, 131882, 263210, 525866, 1050666, 2100266, 4198442, 8394794, 16785450, 33566762, 67125290, 134242346, 268468266, 536920106, 1073807402, 2147581994, 4295098410 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 6 of A183986.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..200

FORMULA

Conjectures from Colin Barker, Apr 09 2018: (Start)

G.f.: x*(45 - 88*x - 91*x^2 + 176*x^3) / ((1 - x)*(1 - 2*x)*(1 - 2*x^2)).

a(n) = 3*2^(n/2-1) + 2^(n-1) + 42 for n even.

a(n) = 2^(n-1) + 2^((n+1)/2) + 42 for n odd.

a(n) = 3*a(n-1) - 6*a(n-3) + 4*a(n-4) for n>4.

(End)

EXAMPLE

Some solutions for 5 X 7.

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

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

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

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

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

CROSSREFS

Cf. A183986.

Sequence in context: A252721 A042011 A031064 * A116334 A291788 A291787

Adjacent sequences:  A183980 A183981 A183982 * A183984 A183985 A183986

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 08 2011

STATUS

approved

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Last modified April 10 19:06 EDT 2021. Contains 342853 sequences. (Running on oeis4.)