A262267 Number of (n+2) X (1+2) 0..1 arrays with each row and column divisible by 5, read as a binary number with top and left being the most significant bits.

2, 4, 7, 13, 26, 52, 103, 205, 410, 820, 1639, 3277, 6554, 13108, 26215, 52429, 104858, 209716, 419431, 838861, 1677722, 3355444, 6710887, 13421773, 26843546, 53687092, 107374183, 214748365, 429496730, 858993460, 1717986919, 3435973837

Offset

1,1

Comments

Column 1 of A262274.

Links

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

Formula

Empirical: a(n) = 3*a(n-1) - 3*a(n-2) + 3*a(n-3) - 2*a(n-4).

Conjectures from Colin Barker, Feb 21 2018: (Start)

G.f.: x*(2 - 2*x + x^2 - 2*x^3) / ((1 - x)*(1 - 2*x)*(1 + x^2)).

a(n) = 1/2 + 2^(2+n)/5 - (1/20-i/20)*((1+2*i)*(-i)^n + (2+i)*i^n) where i=sqrt(-1).

(End)

Example

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

Crossrefs

Cf. A262274.

Sequence in context: A303059 A099155 A342764 * A068031 A293314 A023431

Adjacent sequences: A262264 A262265 A262266 * A262268 A262269 A262270

Keyword

nonn

Author

R. H. Hardin, Sep 17 2015

Status

approved