A262421 - OEIS

A262421

Number of (2+1) X (n+1) 0..1 arrays with each row divisible by 3 and column not divisible by 3, read as a binary number with top and left being the most significant bits.

5, 4, 45, 114, 709, 2892, 15293, 72370, 367125, 1808844, 9078925, 45214674, 226307429, 1130307532, 5653140573, 28257215730, 141297157045, 706426855884, 3532211260205, 17660645718034, 88303765183749, 441515959527372

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OFFSET

1,1

LINKS

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

FORMULA

Empirical: a(n) = 5*a(n-1) + 12*a(n-2) - 60*a(n-3) - 39*a(n-4) + 195*a(n-5) + 28*a(n-6) - 140*a(n-7).

Empirical g.f.: x*(5 - 21*x - 35*x^2 + 141*x^3 + 34*x^4 - 140*x^5) / ((1 - x)*(1 + x)*(1 - 2*x)*(1 + 2*x)*(1 - 5*x)*(1 - 7*x^2)). - Colin Barker, Dec 31 2018

EXAMPLE

Some solutions for n=4:

..1..1..0..0..0....0..1..1..0..0....1..1..1..1..0....1..1..0..1..1

..0..1..0..0..1....1..1..0..1..1....1..1..0..0..0....0..1..1..0..0

..1..1..1..1..0....0..1..1..0..0....1..1..0..1..1....1..1..0..0..0

CROSSREFS

Row 2 of A262420.

Sequence in context: A189748 A304151 A223527 * A305170 A192344 A181613

Adjacent sequences: A262418 A262419 A262420 * A262422 A262423 A262424

KEYWORD

nonn

AUTHOR

R. H. Hardin, Sep 22 2015

STATUS

approved