The OEIS is supported by the many generous donors to the OEIS Foundation.

 Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 59th year, we have over 358,000 sequences, and we’ve crossed 10,300 citations (which often say “discovered thanks to the OEIS”). Other ways to Give
 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A234875 Number of (n+1) X (1+1) 0..4 arrays with every 2 X 2 subblock having its diagonal sum differing from its antidiagonal sum by 1, with no adjacent elements equal (constant-stress tilted 1 X 1 tilings). 1
 32, 68, 128, 268, 512, 1068, 2048, 4268, 8192, 17068, 32768, 68268, 131072, 273068, 524288, 1092268, 2097152, 4369068, 8388608, 17476268, 33554432, 69905068, 134217728, 279620268, 536870912, 1118481068, 2147483648, 4473924268 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = 5*a(n-2) - 4*a(n-4). Conjectures from Colin Barker, Oct 16 2018: (Start) G.f.: 4*x*(8 + 17*x - 8*x^2 - 18*x^3) / ((1 - x)*(1 + x)*(1 - 2*x)*(1 + 2*x)). a(n) = (4 + (-2)^n + 49*2^n) / 3 for n even. a(n) = ((-2)^n + 49*2^n) / 3 for n odd. (End) EXAMPLE Some solutions for n=4: 3 2 3 2 0 1 1 3 4 3 2 3 4 2 1 0 1 3 0 2 2 0 2 0 2 4 0 1 2 0 0 2 1 0 4 2 0 1 2 3 4 1 4 3 1 2 2 4 4 3 2 3 4 2 1 0 2 4 0 2 2 0 3 1 2 4 0 1 2 0 0 2 1 0 3 1 1 2 3 4 4 3 4 3 0 3 1 3 4 1 3 4 4 2 1 0 2 4 0 2 CROSSREFS Column 1 of A234882. Sequence in context: A043935 A044134 A044515 * A153981 A264589 A100017 Adjacent sequences: A234872 A234873 A234874 * A234876 A234877 A234878 KEYWORD nonn AUTHOR R. H. Hardin, Jan 01 2014 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified December 7 23:32 EST 2022. Contains 358671 sequences. (Running on oeis4.)