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A209649 Number of n X 7 0..1 arrays avoiding 0 0 1 and 1 0 0 horizontally and 0 0 1 and 1 0 1 vertically. 2
35, 1225, 7210, 24990, 65765, 145775, 287140, 518700, 876855, 1406405, 2161390, 3205930, 4615065, 6475595, 8886920, 11961880, 15827595, 20626305, 26516210, 33672310, 42287245, 52572135, 64757420, 79093700, 95852575, 115327485 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 7 of A209650.

LINKS

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

FORMULA

Empirical: a(n) = 7*n^5 + 70*n^4 + (35/3)*n^3 - (105/2)*n^2 - (7/6)*n.

Conjectures from Colin Barker, Mar 07 2018: (Start)

G.f.: 35*x*(1 + x)*(1 + 28*x - 17*x^2) / (1 - x)^6.

a(n) = 6*a(n-1) - 15*a(n-2) + 20*a(n-3) - 15*a(n-4) + 6*a(n-5) - a(n-6) for n>6.

(End)

EXAMPLE

Some solutions for n=4:

  1 0 1 0 1 0 1     0 1 0 1 1 1 0     1 1 0 1 1 0 1

  0 0 0 0 0 0 0     0 0 0 0 0 0 0     0 0 0 0 0 0 0

  0 0 0 0 0 0 0     0 0 0 0 0 0 0     0 0 0 0 0 0 0

  0 0 0 0 0 0 0     0 0 0 0 0 0 0     0 0 0 0 0 0 0

CROSSREFS

Cf. A209650.

Sequence in context: A207665 A208006 A207568 * A207756 A207937 A208697

Adjacent sequences:  A209646 A209647 A209648 * A209650 A209651 A209652

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 11 2012

STATUS

approved

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Last modified January 19 22:12 EST 2022. Contains 350466 sequences. (Running on oeis4.)