login

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”).

A250794
Number of (n+1) X (5+1) 0..1 arrays with nondecreasing min(x(i,j),x(i,j-1)) in the i direction and nondecreasing absolute value of x(i,j)-x(i-1,j) in the j direction.
1
252, 838, 2776, 9258, 31220, 105954, 361344, 1236058, 4237556, 14549610, 50012080, 172050098, 592248148, 2039649282, 7026884288, 24215293674, 83465955764, 287740551770, 992085339216, 3420905014178, 11796889975188, 40683768017330
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = 10*a(n-1) - 33*a(n-2) + 24*a(n-3) + 79*a(n-4) - 138*a(n-5) - 3*a(n-6) + 100*a(n-7) - 18*a(n-8) - 20*a(n-9).
Empirical g.f.: 2*x*(126 - 841*x + 1356*x^2 + 1552*x^3 - 4886*x^4 + 609*x^5 + 3484*x^6 - 580*x^7 - 640*x^8) / ((1 - x)^2*(1 - 2*x)*(1 - 2*x - x^2)*(1 - 2*x - 2*x^2)*(1 - 2*x - 5*x^2)). - Colin Barker, Nov 20 2018
EXAMPLE
Some solutions for n=4:
..0..0..0..0..0..1....0..1..0..1..0..0....1..0..1..0..1..0....1..0..0..0..0..0
..0..0..0..0..0..1....0..1..0..1..0..1....1..0..1..0..0..1....1..0..0..0..0..0
..0..0..0..0..1..0....0..1..0..1..1..0....1..0..1..0..1..0....1..0..0..0..0..1
..0..0..0..1..0..1....0..1..0..1..1..1....0..1..0..1..0..1....1..0..0..0..1..0
..0..0..0..0..1..0....0..1..0..1..1..1....0..0..1..0..1..0....1..0..0..0..1..0
CROSSREFS
Column 5 of A250797.
Sequence in context: A254467 A242570 A046379 * A245858 A200884 A275316
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 27 2014
STATUS
approved