A253501 - OEIS

The OEIS is supported by the many generous donors to the OEIS Foundation.

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

Other ways to Give

A253501

Number of (7+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.

48293, 55362, 68992, 89339, 133284, 224747, 415106, 817442, 1686914, 3620258, 8070146, 18719522, 45267074, 114108578, 299030786, 810592802, 2258869634, 6430881698, 18601281026, 54421205282, 160498430594, 475965011618

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..201

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) + 5274*2^(n-1) + 45170 for n>6.

Empirical g.f.: x*(48293 - 234396*x + 268043*x^2 - 5389*x^3 + 23990*x^4 - 6180*x^5 - 3286*x^6 - 681*x^7 - 54*x^8) / ((1 - x)*(1 - 2*x)*(1 - 3*x)). - Colin Barker, Dec 16 2018

EXAMPLE

Some solutions for n=4:

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

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

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

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

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

..1..2..2..1..1....2..2..2..2..1....1..1..1..1..1....2..2..2..2..2

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

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

CROSSREFS

Row 7 of A253495.

Sequence in context: A221556 A227701 A253494 * A253455 A233890 A031867

Adjacent sequences: A253498 A253499 A253500 * A253502 A253503 A253504

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 02 2015

STATUS

approved