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A106354
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Number of compositions of n into 5 parts such that no two adjacent parts are equal.
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1
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1, 3, 15, 30, 68, 119, 204, 316, 489, 696, 987, 1340, 1801, 2348, 3035, 3833, 4812, 5935, 7273, 8792, 10576, 12576, 14887, 17465, 20401, 23651, 27319, 31349, 35861, 40791, 46260, 52212, 58776, 65881, 73667, 82068, 91225, 101067, 111748, 123185
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OFFSET
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7,2
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LINKS
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A. Knopfmacher and H. Prodinger, On Carlitz compositions, European Journal of Combinatorics, Vol. 19, 1998, pp. 579-589.
Index entries for linear recurrences with constant coefficients, signature (1,1,0,0,-1,-1,-1,1,1,1,0,0,-1,-1,1).
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FORMULA
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G.f.: -x^7*(16*x^8 +12*x^7 +21*x^6 +22*x^5 +23*x^4 +12*x^3 +11*x^2 +2*x +1) / ((x -1)^5*(x +1)^2*(x^2 +1)*(x^2 +x +1)*(x^4 +x^3 +x^2 +x +1)). [Colin Barker, Feb 13 2013]
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MATHEMATICA
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LinearRecurrence[{1, 1, 0, 0, -1, -1, -1, 1, 1, 1, 0, 0, -1, -1, 1}, {1, 3, 15, 30, 68, 119, 204, 316, 489, 696, 987, 1340, 1801, 2348, 3035}, 40] (* Harvey P. Dale, Dec 15 2013 *)
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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