A253499 - OEIS

A253499

Number of (5+1) X (n+1) 0..2 arrays with every 2 X 2 subblock diagonal minus antidiagonal sum nondecreasing horizontally, vertically and ne-to-sw antidiagonally.

8501, 9654, 13528, 19475, 32652, 61955, 127898, 281402, 653210, 1591226, 4050458, 10718522, 29303450, 82219706, 235291418, 683152442, 2004027290, 5921235386, 17582026778, 52382735162, 156421528730, 467811246266, 1400527072538

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OFFSET

1,1

LINKS

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

FORMULA

Empirical: a(n) = 6*a(n-1) - 11*a(n-2) + 6*a(n-3) for n>9.

Empirical: a(n) = 400*3^(n-3) + 1386*2^(n-1) + 6794 for n>6.

Empirical g.f.: x*(8501 - 41352*x + 49115*x^2 - 6505*x^3 + 6686*x^4 - 900*x^5 - 1510*x^6 - 393*x^7 - 54*x^8) / ((1 - x)*(1 - 2*x)*(1 - 3*x)). - Colin Barker, Dec 16 2018

EXAMPLE

Some solutions for n=4:

..2..1..1..1..2....1..0..1..0..0....2..2..2..2..2....1..1..1..1..0

..1..0..0..0..1....1..0..1..0..0....2..2..2..2..2....1..1..1..1..0

..1..0..0..0..1....2..1..2..1..1....2..2..2..2..2....2..2..2..2..1

..2..1..1..1..2....1..0..1..0..0....0..0..0..0..0....1..1..1..1..0

..1..0..0..0..1....2..1..2..1..1....1..1..1..1..1....2..2..2..2..1

..1..0..0..0..1....1..0..1..0..1....1..1..1..1..1....0..0..0..0..2

CROSSREFS

Row 5 of A253495.

Sequence in context: A151643 A031590 A322160 * A253492 A253453 A348605

Adjacent sequences: A253496 A253497 A253498 * A253500 A253501 A253502

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 02 2015

STATUS

approved