cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A251269 Number of (2+1) X (n+1) 0..1 arrays with no 2 X 2 subblock having x11-x00 less than x10-x01.

Original entry on oeis.org

35, 114, 313, 772, 1775, 3894, 8277, 17224, 35339, 71834, 145137, 292108, 586471, 1175678, 2354637, 4713168, 9430915, 18867170, 37740521, 75488148, 150984415, 301978054, 603966533, 1207944792, 2415902715, 4831820074, 9663656417
Offset: 1

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Author

R. H. Hardin, Dec 01 2014

Keywords

Examples

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

Crossrefs

Row 2 of A251268.

Formula

Empirical: a(n) = 6*a(n-1) - 14*a(n-2) + 16*a(n-3) - 9*a(n-4) + 2*a(n-5).
Conjectures from Colin Barker, Nov 27 2018: (Start)
G.f.: x*(35 - 96*x + 119*x^2 - 70*x^3 + 16*x^4) / ((1 - x)^4*(1 - 2*x)).
a(n) = 8*(9*2^n-8) - (109*n)/3 - 8*n^2 - (2*n^3)/3.
(End)