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 A138978 Number of 3 X n matrices containing a 1 in the top left entry, all entries are integer values and adjacent entries differ by at most 1. 5
 9, 121, 1665, 22979, 317259, 4380445, 60481881, 835088891, 11530288395, 159201677509, 2198138788809, 30350271502115, 419054058355851, 5785987905016141, 79888633386248025, 1103043049708026539, 15230001039404897259, 210284568423392013685, 2903453493049800669321 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Horizontally or vertically adjacent entries can differ by at most 1. Diagonally adjacent entries thus differ by at most 2. LINKS Alois P. Heinz, Table of n, a(n) for n = 1..800 Index entries for linear recurrences with constant coefficients, signature (16,-31,10). FORMULA a(n)=b(n)+c(n)+d(n), where b(1)=1, c(1)=6, d(1)=2, b(n+1)=3*b(n)+2*c(n)+1*d(n) c(n+1)=12*b(n)+10*c(n)+6*d(n) d(n+1)=2*b(n)+2*c(n)+3*d(n) G.f.: -x*(8*x^2-23*x+9) / (10*x^3-31*x^2+16*x-1). [Colin Barker, Dec 03 2012] MAPLE a:= n-> (Matrix([1, 6, 2]). Matrix([[3, 12, 2], [2, 10, 2], [1, 6, 3]])^(n-1) .Matrix([[1], [1], [1]]))[1, 1]: seq(a(n), n=1..20); # Alois P. Heinz, Aug 28 2008] CROSSREFS Cf. A138977, A138979. Sequence in context: A103930 A302941 A183514 * A046184 A084769 A246467 Adjacent sequences:  A138975 A138976 A138977 * A138979 A138980 A138981 KEYWORD nonn,easy AUTHOR Wayne VanWeerthuizen, Apr 05 2008 EXTENSIONS More terms from Alois P. Heinz, Aug 28 2008 STATUS approved

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Last modified May 25 20:58 EDT 2020. Contains 334597 sequences. (Running on oeis4.)