A270257 Number of 2X2X2 triangular 0..n arrays with some element plus some adjacent element totalling n exactly once.

0, 12, 24, 48, 72, 108, 144, 192, 240, 300, 360, 432, 504, 588, 672, 768, 864, 972, 1080, 1200, 1320, 1452, 1584, 1728, 1872, 2028, 2184, 2352, 2520, 2700, 2880, 3072, 3264, 3468, 3672, 3888, 4104, 4332, 4560, 4800, 5040, 5292, 5544, 5808, 6072, 6348, 6624

Offset

1,2

Comments

Row 2 of A270256.

Links

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

Formula

Empirical: a(n) = 2*a(n-1) -2*a(n-3) +a(n-4)

Empirical for n mod 2 = 0: a(n) = 3*n^2

Empirical for n mod 2 = 1: a(n) = 3*n^2 - 3

Example

Some solutions for n=4
...2....3....0....3....0....1....2....1....3....0....4....3....0....4....3....2
..3.2..4.0..4.1..2.2..4.3..4.0..2.1..0.3..4.1..1.4..2.0..2.1..2.2..2.2..1.4..2.0

Crossrefs

Cf. A270256.

Sequence in context: A181924 A386223 A367105 * A367361 A180617 A081808

Adjacent sequences: A270254 A270255 A270256 * A270258 A270259 A270260

Keyword

nonn

Author

R. H. Hardin, Mar 14 2016

Status

approved