A194932 Number of lower triangles of a 3 X 3 0..n array with no element differing from any of its horizontal or vertical neighbors by more than one.

64, 217, 386, 557, 728, 899, 1070, 1241, 1412, 1583, 1754, 1925, 2096, 2267, 2438, 2609, 2780, 2951, 3122, 3293, 3464, 3635, 3806, 3977, 4148, 4319, 4490, 4661, 4832, 5003, 5174, 5345, 5516, 5687, 5858, 6029, 6200, 6371, 6542, 6713, 6884, 7055, 7226

Offset

1,1

Comments

Row 3 of A194931.

Links

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

Formula

Empirical: a(n) = 171*n - 127 for n>2.

Empirical g.f.: x*(64 + 89*x + 16*x^2 + 2*x^3) / (1 - x)^2. - Colin Barker, May 05 2018

Example

Some solutions for n=4:
..1......0......3......3......1......0......1......3......1......4......3
..2.2....1.2....3.2....3.4....1.1....1.2....0.1....4.3....1.2....3.4....2.2
..3.2.2..2.3.4..2.3.3..3.4.3..2.1.0..1.1.2..0.0.1..4.3.4..0.1.1..2.3.2..3.2.2

Crossrefs

Cf. A194931.

Sequence in context: A245991 A186637 A295021 * A016994 A258732 A279714

Adjacent sequences: A194929 A194930 A194931 * A194933 A194934 A194935

Keyword

nonn

Author

R. H. Hardin, Sep 05 2011

Status

approved