A195234 Number of lower triangles of a 4 X 4 0..n array with each element differing from all of its diagonal, vertical, antidiagonal and horizontal neighbors by one or less.

1024, 3151, 5428, 7705, 9982, 12259, 14536, 16813, 19090, 21367, 23644, 25921, 28198, 30475, 32752, 35029, 37306, 39583, 41860, 44137, 46414, 48691, 50968, 53245, 55522, 57799, 60076, 62353, 64630, 66907, 69184, 71461, 73738, 76015, 78292, 80569

Offset

1,1

Comments

Row 4 of A195232.

Links

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

Formula

Empirical: a(n) = 2277*n - 1403 for n>1.

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

G.f.: x*(1024 + 1103*x + 150*x^2) / (1 - x)^2.

a(n) = 2*a(n-1) - a(n-2) for n>3.

(End)

Example

Some solutions for n=4:
..4........3........2........0........2........4........3........0
..3.3......2.2......2.3......1.1......1.1......3.4......2.3......1.1
..4.3.3....2.3.2....2.2.3....2.1.1....0.1.0....3.3.4....3.3.2....2.1.0
..3.3.2.3..3.3.2.3..1.2.2.3..1.2.2.2..1.0.0.1..4.4.3.4..2.2.3.3..1.1.1.0

Crossrefs

Cf. A195232.

Sequence in context: A366391 A195093 A258734 * A257650 A255664 A358001

Adjacent sequences: A195231 A195232 A195233 * A195235 A195236 A195237

Keyword

nonn

Author

R. H. Hardin, Sep 13 2011

Status

approved