A195249 Number of lower triangles of a 3 X 3 0..n array with each element differing from all of its diagonal, vertical, antidiagonal and horizontal neighbors by two or less.

64, 729, 1682, 2729, 3776, 4823, 5870, 6917, 7964, 9011, 10058, 11105, 12152, 13199, 14246, 15293, 16340, 17387, 18434, 19481, 20528, 21575, 22622, 23669, 24716, 25763, 26810, 27857, 28904, 29951, 30998, 32045, 33092, 34139, 35186, 36233, 37280, 38327

Offset

1,1

Comments

Row 3 of A195248.

Links

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

Formula

Empirical: a(n) = 1047*n - 1459 for n>2.

Conjectures from Colin Barker, May 06 2018: (Start)

G.f.: x*(64 + 601*x + 288*x^2 + 94*x^3) / (1 - x)^2.

a(n) = 2*a(n-1) - a(n-2) for n>4.

(End)

Example

Some solutions for n=5:
..2......1......0......0......4......5......1......1......5......3
..3.4....2.3....2.0....0.2....5.4....3.5....1.3....2.3....3.3....2.2
..4.4.4..2.1.2..1.1.1..1.1.3..4.4.5..5.5.3..2.1.3..4.3.4..2.3.3..0.0.2

Crossrefs

Cf. A195248.

Sequence in context: A354178 A367803 A161860 * A223953 A224137 A016899

Adjacent sequences: A195246 A195247 A195248 * A195250 A195251 A195252

Keyword

nonn

Author

R. H. Hardin, Sep 13 2011

Status

approved