A262753 Number of (n+2) X (2+2) 0..1 arrays with each row divisible by 5 and each column divisible by 7, read as a binary number with top and left being the most significant bits.

4, 9, 25, 100, 361, 1369, 5476, 21609, 85849, 343396, 1371241, 5480281, 21921124, 87665769, 350625625, 1402502500, 5609860201, 22439141209, 89756564836, 359025060969, 1436097847129, 5744391388516, 22977555967081, 91910204694361

Offset

1,1

Links

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

Formula

Empirical: a(n) = 4*a(n-1) + 9*a(n-3) - 36*a(n-4) - 8*a(n-6) + 32*a(n-7).

Empirical g.f.: x*(4 - 7*x - 11*x^2 - 36*x^3 + 24*x^4 + 24*x^5 + 32*x^6) / ((1 - x)*(1 - 2*x)*(1 - 4*x)*(1 + x + x^2)*(1 + 2*x + 4*x^2)). - Colin Barker, Dec 31 2018

Example

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

Crossrefs

Column 2 of A262759.

Sequence in context: A355799 A117678 A167045 * A055851 A025494 A087374

Adjacent sequences: A262750 A262751 A262752 * A262754 A262755 A262756

Keyword

nonn

Author

R. H. Hardin, Sep 30 2015

Status

approved