A194933 Number of lower triangles of a 4 X 4 0..n array with no element differing from any of its horizontal or vertical neighbors by more than one.

1024, 5873, 12474, 19379, 26316, 33255, 40194, 47133, 54072, 61011, 67950, 74889, 81828, 88767, 95706, 102645, 109584, 116523, 123462, 130401, 137340, 144279, 151218, 158157, 165096, 172035, 178974, 185913, 192852, 199791, 206730, 213669

Offset

1,1

Comments

Row 4 of A194931.

Links

R. H. Hardin, Table of n, a(n) for n = 1..200

Formula

Empirical: a(n) = 6939*n - 8379 for n>4.

Empirical g.f.: x*(1024 + 3825*x + 1752*x^2 + 304*x^3 + 32*x^4 + 2*x^5) / (1 - x)^2. - Colin Barker, May 05 2018

Example

Some solutions for n=4:
..2........0........1........1........2........2........0........2
..1.2......0.1......0.0......2.3......1.2......1.0......0.0......2.1
..2.3.4....0.1.1....1.1.1....3.3.3....1.2.2....0.0.1....1.0.1....2.2.2
..3.3.3.4..0.0.1.1..0.1.1.2..3.2.2.2..0.1.2.1..0.1.2.2..1.0.0.0..2.2.2.3

Crossrefs

Cf. A194931.

Sequence in context: A189071 A214800 A220765 * A231944 A318112 A197711

Adjacent sequences: A194930 A194931 A194932 * A194934 A194935 A194936

Keyword

nonn

Author

R. H. Hardin, Sep 05 2011

Status

approved