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A056834
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a(n) = floor(n^2/7).
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12
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0, 0, 0, 1, 2, 3, 5, 7, 9, 11, 14, 17, 20, 24, 28, 32, 36, 41, 46, 51, 57, 63, 69, 75, 82, 89, 96, 104, 112, 120, 128, 137, 146, 155, 165, 175, 185, 195, 206, 217, 228, 240, 252, 264, 276, 289, 302, 315, 329, 343, 357, 371, 386, 401, 416, 432, 448
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OFFSET
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0,5
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LINKS
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FORMULA
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a(n) = +2*a(n-1) -a(n-2) +a(n-7) -2*a(n-8) +a(n-9).
G.f.: -x^3*(1+x)*(x^2-x+1) / ( (x^6+x^5+x^4+x^3+x^2+x+1)*(x-1)^3 ).
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MATHEMATICA
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Floor[(Range[0, 60]^2)/7] (* or *) LinearRecurrence[{2, -1, 0, 0, 0, 0, 1, -2, 1}, {0, 0, 0, 1, 2, 3, 5, 7, 9}, 60] (* Harvey P. Dale, Jul 21 2014 *)
CoefficientList[Series[-x^3 (1 + x) (x^2 - x + 1)/((x^6 + x^5 + x^4 + x^3 + x^2 + x + 1) (x - 1)^3), {x, 0, 100}], x] (* Vincenzo Librandi, Jul 22 2014 *)
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PROG
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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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