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 A184030 1/16 the number of (n+1) X (n+1) 0..3 arrays with all 2 X 2 subblocks having the same four values. 2
 16, 40, 82, 166, 322, 634, 1234, 2434, 4786, 9490, 18802, 37426, 74482, 148594, 296434, 592114, 1182706, 2363890, 4724722, 9446386, 18886642, 37767154, 75522034, 151031794, 302039026, 604053490, 1208057842, 2416066546, 4832034802, 9663971314, 19327746034, 38655295474 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Andrew Howroyd, Table of n, a(n) for n = 1..1000 Index entries for linear recurrences with constant coefficients, signature (3,0,-6,4). FORMULA From Andrew Howroyd, Mar 09 2024: (Start) a(n) = 3*a(n-1) - 6*a(n-3) + 4*a(n-4). G.f.: 2*x*(8 - 4*x - 19*x^2 + 8*x^3)/((1 - x)*(1 - 2*x)*(1 - 2*x^2)). (End) EXAMPLE Some solutions for 4X4 ..1..3..1..1....3..0..3..0....2..2..2..2....0..0..0..0....1..0..0..0 ..1..1..1..3....0..1..0..1....1..3..1..3....2..2..2..2....0..2..1..2 ..1..3..1..1....0..3..0..3....2..2..2..2....0..0..0..0....1..0..0..0 ..1..1..1..3....1..0..1..0....3..1..3..1....2..2..2..2....0..2..1..2 PROG (PARI) Vec(2*(8 - 4*x - 19*x^2 + 8*x^3)/((1 - x)*(1 - 2*x)*(1 - 2*x^2)) + O(x^30)) \\ Andrew Howroyd, Mar 09 2024 CROSSREFS Diagonal of A184039. Sequence in context: A174321 A258258 A086046 * A350284 A182461 A205065 Adjacent sequences: A184027 A184028 A184029 * A184031 A184032 A184033 KEYWORD nonn,easy AUTHOR R. H. Hardin, Jan 08 2011 EXTENSIONS a(14) onwards from Andrew Howroyd, Mar 09 2024 STATUS approved

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Last modified July 25 11:18 EDT 2024. Contains 374588 sequences. (Running on oeis4.)