A250677 Number of (1+1) X (n+1) 0..3 arrays with nondecreasing 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.

104, 669, 3927, 22119, 120233, 637948, 3321772, 17052553, 86573591, 435717423, 2177845221, 10825761528, 53576004128, 264200974309, 1299108852679, 6372932446759, 31203614429489, 152543921033076, 744788303718996

Offset

1,1

Comments

Row 1 of A250676.

Links

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

Formula

Empirical: a(n) = 10*a(n-1) - 21*a(n-2) - 54*a(n-3) + 155*a(n-4) + 118*a(n-5) - 228*a(n-6) - 144*a(n-7).

Empirical g.f.: x*(104 - 371*x - 579*x^2 + 2514*x^3 + 1516*x^4 - 3792*x^5 - 2304*x^6) / ((1 - 4*x)*(1 - x - x^2)*(1 - 2*x - 4*x^2)*(1 - 3*x - 9*x^2)). - Colin Barker, Mar 19 2018

Example

Some solutions for n=4:
  2 1 3 1 1    1 2 1 0 1    1 2 2 0 0    1 1 1 1 3
  3 2 2 3 3    1 3 2 1 2    2 3 1 1 1    1 2 3 3 1

Crossrefs

Cf. A250676.

Sequence in context: A250691 A250692 A250676 * A206021 A206014 A106298

Adjacent sequences: A250674 A250675 A250676 * A250678 A250679 A250680

Keyword

nonn

Author

R. H. Hardin, Nov 26 2014

Status

approved