A274751 Number of 4 X n 0..2 arrays with no element equal to any value at offset (-1,-2) (0,-1) or (-1,0) and new values introduced in order 0..2.

4, 27, 144, 813, 4554, 25585, 143634, 806695, 4529786, 25438375, 142850048, 802197187, 4504820208, 25297392889, 142060454416, 797757713921, 4479903521254, 25157436233205, 141274594599246, 793344420605515

Offset

1,1

Links

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

Formula

Empirical: a(n) = 2*a(n-1) + 20*a(n-2) + 10*a(n-3) - 44*a(n-4) - 20*a(n-5) + 31*a(n-6) + 2*a(n-7) - 4*a(n-8).

Empirical g.f.: x*(4 + 19*x + 10*x^2 - 55*x^3 - 46*x^4 + 45*x^5 + 6*x^6 - 6*x^7) / ((1 + x - x^2)*(1 - 3*x - 16*x^2 + 3*x^3 + 25*x^4 - 2*x^5 - 4*x^6)). - Colin Barker, Jan 30 2019

Example

Some solutions for n=4:
..0..1..0..1. .0..1..0..2. .0..1..0..1. .0..1..0..2. .0..1..0..1
..2..0..1..0. .1..2..1..0. .2..0..1..0. .1..0..2..0. .1..2..1..2
..0..2..0..1. .0..1..2..1. .0..1..0..1. .0..1..0..1. .2..0..2..1
..2..1..2..0. .1..0..1..0. .1..2..1..0. .2..0..2..0. .0..1..0..2

Crossrefs

Row 4 of A274749.

Sequence in context: A366486 A240194 A278358 * A015534 A306054 A218274

Adjacent sequences: A274748 A274749 A274750 * A274752 A274753 A274754

Keyword

nonn

Author

R. H. Hardin, Jul 04 2016

Status

approved