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A203729 Number of (n+1) X 3 0..7 arrays with every 2 X 2 subblock having equal diagonal elements or equal antidiagonal elements. 1
14400, 539456, 19071424, 681461824, 24301391808, 866928276544, 30924651270080, 1103143816649792, 39351237685123008, 1403734121231217728, 50073884084764590016, 1786231359311202929728, 63718293832198857385920 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 2 of A203732.

LINKS

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

FORMULA

Empirical: a(n) = 29*a(n-1) +238*a(n-2).

Empirical g.f.: 64*x*(225 + 1904*x) / (1 - 29*x - 238*x^2). - Colin Barker, Jun 04 2018

EXAMPLE

Some solutions for n=4:

..3..0..1....0..4..1....2..5..1....5..3..2....0..5..0....3..1..5....0..2..5

..0..0..0....2..0..4....6..2..5....2..5..3....3..0..5....7..3..1....0..0..2

..2..0..5....3..2..0....4..6..2....6..2..5....1..3..0....1..7..3....2..0..0

..1..2..0....0..3..2....3..4..6....4..6..2....7..1..3....3..1..7....4..2..0

..1..1..2....1..0..3....2..3..4....6..2..5....4..7..1....7..3..1....4..4..2

CROSSREFS

Cf. A203732.

Sequence in context: A237372 A250851 A226286 * A144649 A166371 A234487

Adjacent sequences:  A203726 A203727 A203728 * A203730 A203731 A203732

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 05 2012

STATUS

approved

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Last modified June 28 07:25 EDT 2022. Contains 354903 sequences. (Running on oeis4.)