A214541 Number of 3X3X3 triangular 0..n arrays with no element lying outside the (possibly reversed) range delimited by its sw and se neighbors, and every horizontal row having the same average value

2, 15, 38, 79, 152, 263, 418, 643, 942, 1329, 1832, 2463, 3234, 4185, 5326, 6677, 8280, 10153, 12314, 14817, 17678, 20923, 24608, 28757, 33394, 38587, 44358, 50739, 57800, 65571, 74082, 83415, 93598, 104669, 116712, 129763, 143858, 159093, 175502

Offset

1,1

Comments

Row 3 of A214540

Links

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

Formula

Empirical: a(n) = 2*a(n-1) -3*a(n-4) +3*a(n-6) -2*a(n-9) +a(n-10).

Empirical: G.f. -x*(2+11*x+8*x^2+3*x^3+4*x^5-x^7-2*x^8+x^9) / ( (1+x)*(1+x+x^2)^2*(x-1)^5 ). - R. J. Mathar, Jul 23 2012

Example

Some solutions for n=4
....3......2......3......2......3......3......1......0......2......2......1
...2.4....3.1....4.2....3.1....3.3....3.3....1.1....0.0....3.1....2.2....0.2
..4.1.4..3.3.0..4.1.4..2.4.0..3.2.4..3.3.3..1.1.1..0.0.0..3.1.2..1.3.2..0.1.2

Crossrefs

Sequence in context: A064113 A007217 A295367 * A180223 A070009 A070170

Adjacent sequences: A214538 A214539 A214540 * A214542 A214543 A214544

Keyword

nonn

Author

R. H. Hardin Jul 20 2012

Status

approved