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A187325
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a(n) = floor(n/2) + floor(n/3) + floor(n/4) + floor(n/5).
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1
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0, 0, 1, 2, 4, 5, 7, 7, 9, 10, 12, 12, 15, 15, 16, 18, 20, 20, 22, 22, 25, 26, 27, 27, 30, 31, 32, 33, 35, 35, 38, 38, 40, 41, 42, 43, 46, 46, 47, 48, 51, 51, 53, 53, 55, 57, 58, 58, 61, 61, 63, 64, 66, 66, 68, 69, 71, 72, 73, 73, 77, 77, 78, 79, 81, 82, 84, 84, 86, 87
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OFFSET
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0,4
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LINKS
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FORMULA
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a(n) = floor(n/2) + floor(n/3) + floor(n/4) + floor(n/5).
a(n) = -a(n-1) - a(n-2) + a(n-4) + 2*a(n-5) + 2*a(n-6) + a(n-7) - a(n-9) - a(n-10) - a(n-11).
G.f.: x^2*(2*x^4 + 3*x^3 + 3*x^2 + 2*x + 1)*(2*x^4 + x^3 + 2*x^2 + x + 1) / ( (1+x)*(1 + x + x^2)*(x^4 + x^3 + x^2 + x + 1)*(x^2+1)*(x-1)^2 ). - R. J. Mathar, Mar 08 2011
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MATHEMATICA
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Table[Floor[n/2]+Floor[n/3]+Floor[n/4]+Floor[n/5], {n, 0, 120}]
Table[Total[Floor[n/Range[2, 5]]], {n, 0, 120}] (* Harvey P. Dale, Nov 22 2015 *)
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PROG
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(Magma) [Floor(n/2)+Floor(n/3)+Floor(n/4)+Floor(n/5): n in [0..130] ]; // Vincenzo Librandi, Jul 18 2011
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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