A184036 1/16 the number of (n+1) X 7 0..3 arrays with all 2 X 2 subblocks having the same four values.

325, 337, 358, 400, 478, 634, 934, 1534, 2710, 5062, 9718, 19030, 37558, 74614, 148534, 296374, 591670, 1182262, 2362678, 4723510, 9443638, 18883894, 37761334, 75516214, 151019830, 302027062, 604029238, 1208033590, 2416017718, 4831985974

Offset

1,1

Comments

Column 6 of A184039.

Links

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

Formula

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

Conjectures from Colin Barker, Apr 10 2018: (Start)

G.f.: x*(325 - 638*x - 653*x^2 + 1276*x^3) / ((1 - x)*(1 - 2*x)*(1 - 2*x^2)).

a(n) = 9*2^(n/2-1) + 9*2^(n-1) + 310 for n even.

a(n) = 9*2^(n-1) + 3*2^((n+1)/2) + 310 for n odd.

(End)

Example

Some solutions for 3 X 7:
..1..2..2..2..2..3..1....3..3..3..1..3..1..0....2..2..2..1..3..1..3
..2..3..1..3..1..2..2....0..1..0..3..0..3..3....3..1..3..2..2..2..2
..1..2..2..2..2..3..1....3..3..3..1..3..1..0....2..2..2..1..3..1..3

Crossrefs

Cf. A184039.

Sequence in context: A253433 A253440 A253157 * A159844 A000443 A097101

Adjacent sequences: A184033 A184034 A184035 * A184037 A184038 A184039

Keyword

nonn

Author

R. H. Hardin, Jan 08 2011

Status

approved