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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. 4
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 (list; graph; refs; listen; history; text; internal format)
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: A251654 A303059 A099155 * A068031 A293314 A023431

Adjacent sequences:  A262264 A262265 A262266 * A262268 A262269 A262270

KEYWORD

nonn

AUTHOR

R. H. Hardin, Sep 17 2015

STATUS

approved

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Last modified November 18 02:02 EST 2019. Contains 329242 sequences. (Running on oeis4.)