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A081199
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5th binomial transform of (0,1,0,1,...), A000035.
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8
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0, 1, 10, 76, 520, 3376, 21280, 131776, 807040, 4907776, 29708800, 179301376, 1080002560, 6496792576, 39047864320, 234555621376, 1408407470080, 8454739787776, 50745618595840, 304542431051776, 1827529464217600
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OFFSET
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0,3
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COMMENTS
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Binomial transform of A005059.
Conjecture (verified up to a(9)): Number of collinear 4-tuples of points in a 4 X 4 X 4 X ... n-dimensional cubic grid. - R. H. Hardin, May 24 2010
a(n) is also the total number of words of length n, over an alphabet of six letters, of which one of them appears an odd number of times. See a Lekraj Beedassy, Jul 22 2003, comment on A006516 (4-letter case), and the Balakrishnan reference there. For the 2-, 3-, 5- and 7-letter case analogs see A131577, A003462, A005059 and A081200, respectively. - Wolfdieter Lang, Jul 16 2017
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LINKS
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Vincenzo Librandi, Table of n, a(n) for n = 0..200
Index entries for linear recurrences with constant coefficients, signature (10,-24).
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FORMULA
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a(n) = 10*a(n-1) - 24*a(n-2) with n>1, a(0)=0, a(1)=1.
G.f.: x/((1-4*x)*(1-6*x)).
a(n) = 6^n/2 - 4^n/2.
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MAPLE
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seq(add(2^(2*n-k)*binomial(n, k)/2, k=1..n), n=0..20); # Zerinvary Lajos, Apr 18 2009
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MATHEMATICA
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CoefficientList[Series[x / ((1 - 4 x) (1 - 6 x)), {x, 0, 30}], x] (* Vincenzo Librandi, Aug 07 2013 *)
LinearRecurrence[{10, -24}, {0, 1}, 21] (* Michael De Vlieger, Jul 16 2017 *)
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PROG
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(Magma) [6^n/2-4^n/2: n in [0..25]]; // Vincenzo Librandi, Aug 07 2013
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CROSSREFS
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Cf. A000035, A003462, A005059, A006516, A016149, A081200 (binomial transform of a(n), and 7-letter case), A131577.
Sequence in context: A061319 A223994 A016149 * A351132 A198692 A215465
Adjacent sequences: A081196 A081197 A081198 * A081200 A081201 A081202
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KEYWORD
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nonn,easy
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AUTHOR
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Paul Barry, Mar 11 2003
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STATUS
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approved
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