A250943 Number of (1+1) X (n+1) 0..2 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.

37, 155, 599, 2247, 8189, 29281, 103093, 358683, 1235935, 4225319, 14350733, 48472137, 162955925, 545627419, 1820560999, 6056081319, 20091759229, 66499907441, 219643052501, 724114352379, 2383286792687, 7832488669255

Offset

1,1

Links

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

Formula

Empirical: a(n) = 6*a(n-1) - 6*a(n-2) - 15*a(n-3) + 14*a(n-4) + 12*a(n-5).

Empirical g.f.: x*(37 - 67*x - 109*x^2 + 138*x^3 + 108*x^4) / ((1 - 3*x)*(1 - x - x^2)*(1 - 2*x - 4*x^2)). - Colin Barker, Nov 23 2018

Example

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

Crossrefs

Row 1 of A250942.

Sequence in context: A178835 A379871 A250942 * A142197 A140011 A296156

Adjacent sequences: A250940 A250941 A250942 * A250944 A250945 A250946

Keyword

nonn

Author

R. H. Hardin, Nov 28 2014

Status

approved