A183640 Number of (n+1) X 8 0..3 arrays with every 2 X 2 subblock summing to 6.

79172, 107992, 170300, 309016, 629132, 1398952, 3333500, 8411896, 22294892, 61632712, 176596700, 521681176, 1582485452, 4916663272, 15625379900, 50774508856, 168710304812, 573264314632, 1991498803100, 7067664046936

Offset

1,1

Comments

Column 7 of A183642.

Links

R. H. Hardin, Table of n, a(n) for n = 1..22

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*(19793 - 170932*x + 465350*x^2 - 393216*x^3) / ((1 - x)*(1 - 2*x)*(1 - 3*x)*(1 - 4*x)).

a(n) = 52670 + 3025*2^(2+n) + 254*3^(1+n) + 4^(1+n).

(End)

Example

Some solutions for 3 X 8:
  2 0 3 0 3 1 3 0      0 3 1 3 1 3 1 3      1 3 1 2 1 1 0 3
  2 2 1 2 1 1 1 2      1 2 0 2 0 2 0 2      2 0 2 1 2 2 3 0
  2 0 3 0 3 1 3 0      0 3 1 3 1 3 1 3      2 2 2 1 2 0 1 2

Crossrefs

Cf. A183642.

Sequence in context: A180973 A264950 A204570 * A157661 A159713 A251208

Adjacent sequences: A183637 A183638 A183639 * A183641 A183642 A183643

Keyword

nonn

Author

R. H. Hardin, Jan 06 2011

Status

approved