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A140066
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a(n) = (5*n^2 - 11*n + 8)/2.
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4
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1, 3, 10, 22, 39, 61, 88, 120, 157, 199, 246, 298, 355, 417, 484, 556, 633, 715, 802, 894, 991, 1093, 1200, 1312, 1429, 1551, 1678, 1810, 1947, 2089, 2236, 2388, 2545, 2707, 2874, 3046, 3223, 3405, 3592, 3784, 3981, 4183, 4390, 4602, 4819, 5041, 5268, 5500
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OFFSET
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1,2
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COMMENTS
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Binomial transform of [1, 2, 5, 0, 0, 0, ...] = A020821.
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LINKS
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FORMULA
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O.g.f.: x*(1+4*x^2)/(1-x)^3. (End)
a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3); a(1)=1, a(2)=3, a(3)=10. - Harvey P. Dale, Jan 28 2012
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EXAMPLE
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a(4) = 22 = (1, 3, 3, 1) dot (1, 2, 5, 0) = (1, + 6 + 15 + 0).
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MAPLE
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MATHEMATICA
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Table[(5n^2-11n+8)/2, {n, 40}] (* or *) LinearRecurrence[{3, -3, 1}, {1, 3, 10}, 40] (* Harvey P. Dale, Jan 28 2012 *)
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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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EXTENSIONS
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STATUS
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approved
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