A226710 Number of n X 1 (-1,0,1) arrays of determinants of 2 X 2 subblocks of some (n+1) X 2 binary array.

3, 9, 25, 67, 181, 491, 1331, 3607, 9775, 26491, 71793, 194565, 527287, 1428991, 3872683, 10495289, 28443095, 77083123, 208901593, 566140471, 1534287165, 4158044205, 11268641233, 30538943065, 82763043409, 224294643719

Offset

1,1

Links

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

Formula

Empirical: a(n) = 2*a(n-1) + a(n-2) + 2*a(n-3) + a(n-4) + a(n-5).

Empirical g.f.: x*(3 + 3*x + 4*x^2 + 2*x^3 + x^4) / (1 - 2*x - x^2 - 2*x^3 - x^4 - x^5). - Colin Barker, Sep 06 2018

Example

Some solutions for n=3:
..0....1....0....1...-1....1...-1...-1....0....0....1....1....0....0....0....1
..1....0...-1...-1...-1....0....0....1...-1....0...-1....0....1....1....0...-1
..1....0....0...-1....0....1....0...-1...-1....1....1...-1...-1....0....0....0

Crossrefs

Column 1 of A226717.

Sequence in context: A085327 A069403 A291021 * A306928 A094292 A295571

Adjacent sequences: A226707 A226708 A226709 * A226711 A226712 A226713

Keyword

nonn

Author

R. H. Hardin, Jun 15 2013

Status

approved