A183635 Number of (n+1) X 3 0..3 arrays with every 2 X 2 subblock summing to 6.

136, 340, 952, 2884, 9256, 31060, 107992, 386404, 1415176, 5281780, 20015032, 76773124, 297329896, 1160228500, 4554034072, 17956283044, 71047145416, 281857767220, 1120444917112, 4460833796164, 17780522733736, 70933703913940

Offset

1,1

Comments

Column 2 of A183642.

Links

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

Formula

Empirical: a(n) = 10*a(n-1) - 35*a(n-2) + 50*a(n-3) - 24*a(n-4).

Conjectures from Colin Barker, Mar 31 2018: (Start)

G.f.: 4*x*(34 - 255*x + 578*x^2 - 384*x^3) / ((1 - x)*(1 - 2*x)*(1 - 3*x)*(1 - 4*x)).

a(n) = 18 + 3*2^(3+n) + 2*3^(2+n) + 4^(1+n).

(End)

Example

Some solutions for 5 X 3:
  2 2 0    0 0 1    1 2 1    1 2 0    0 3 0    3 0 1    3 1 2
  0 2 2    3 3 2    0 3 0    2 1 3    1 2 1    0 3 2    1 1 2
  2 2 0    0 0 1    1 2 1    1 2 0    2 1 2    2 1 0    3 1 2
  0 2 2    3 3 2    3 0 3    0 3 1    3 0 3    0 3 2    1 1 2
  3 1 1    0 0 1    0 3 0    1 2 0    3 0 3    3 0 1    1 3 0

Crossrefs

Cf. A183642.

Sequence in context: A349092 A098215 A247439 * A116223 A124241 A235198

Adjacent sequences: A183632 A183633 A183634 * A183636 A183637 A183638

Keyword

nonn

Author

R. H. Hardin, Jan 06 2011

Status

approved