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A036406
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a(n) = ceiling(n^2/8).
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3
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0, 1, 1, 2, 2, 4, 5, 7, 8, 11, 13, 16, 18, 22, 25, 29, 32, 37, 41, 46, 50, 56, 61, 67, 72, 79, 85, 92, 98, 106, 113, 121, 128, 137, 145, 154, 162, 172, 181, 191, 200, 211, 221, 232, 242, 254, 265, 277, 288, 301, 313, 326, 338, 352, 365, 379, 392
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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) = (1/16)*(2n^2 + 9 - 5(-1)^n - 2(-1)^floor(n/2) + 2(-1)^floor((n-1)/2)). - Ralf Stephan, Jun 10 2005
G.f.: -x*(1-x-x^3+x^2+x^4) / ( (1+x)*(1+x^2)*(x-1)^3 ). - R. J. Mathar, Jan 22 2011
a(n) = 2*a(n-1) - a(n-2) + a(n-4) - 2*a(n-5) + a(n-6); a(0)=0, a(1)=1, a(2)=1, a(3)=2, a(4)=2, a(5)=4. - Harvey P. Dale, Jun 21 2011
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MAPLE
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MATHEMATICA
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Ceiling[Range[0, 60]^2/8] (* or *) LinearRecurrence[{2, -1, 0, 1, -2, 1}, {0, 1, 1, 2, 2, 4}, 60] (* Harvey P. Dale, Jun 21 2011 *)
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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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