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A011850
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a(n) = floor(binomial(n,4)/4).
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1
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0, 0, 0, 0, 0, 1, 3, 8, 17, 31, 52, 82, 123, 178, 250, 341, 455, 595, 765, 969, 1211, 1496, 1828, 2213, 2656, 3162, 3737, 4387, 5118, 5937, 6851, 7866, 8990, 10230, 11594, 13090, 14726, 16511, 18453, 20562
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OFFSET
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0,7
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LINKS
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Index entries for linear recurrences with constant coefficients, signature (5,-10,10,-6,6,-10,10,-6,6,-10,10,-6,6,-10,10,-5,1).
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FORMULA
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a(n) = +5*a(n-1) -10*a(n-2) +10*a(n-3) -6*a(n-4) +6*a(n-5) -10*a(n-6) +10*a(n-7) -6*a(n-8) +6*a(n-9) -10*a(n-10) +10*a(n-11) -6*a(n-12) +6*a(n-13) -10*a(n-14) +10*a(n-15) -5*a(n-16) +a(n-17). [R. J. Mathar, Apr 15 2010]
G.f.: x^5*(-3*x^7-3*x^3+3*x^8-2*x^9+x^10-x^5+2*x^6-2*x+3*x^2+2*x^4+1) / ( (1-x)^5*(x^4+1)*(x^8+1) ). [R. J. Mathar, Apr 15 2010]
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MAPLE
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MATHEMATICA
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Floor[Binomial[Range[0, 50], 4]/4] (* or *) LinearRecurrence[ {5, -10, 10, -6, 6, -10, 10, -6, 6, -10, 10, -6, 6, -10, 10, -5, 1}, {0, 0, 0, 0, 0, 1, 3, 8, 17, 31, 52, 82, 123, 178, 250, 341, 455}, 50] (* Harvey P. Dale, Mar 25 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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