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A141631
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a(n) = 3*n^2 - 4*n + 3.
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6
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2, 7, 18, 35, 58, 87, 122, 163, 210, 263, 322, 387, 458, 535, 618, 707, 802, 903, 1010, 1123, 1242, 1367, 1498, 1635, 1778, 1927, 2082, 2243, 2410, 2583, 2762, 2947, 3138, 3335, 3538, 3747, 3962, 4183, 4410, 4643, 4882, 5127, 5378, 5635, 5898, 6167, 6442
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OFFSET
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1,1
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COMMENTS
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LINKS
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FORMULA
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a(n) = A133146(2*n-2) = (n - 2)^2 + (n - 1)*(n + 1) + n^2.
First differences: a(n+1) - a(n) = A016969(n-1).
G.f.: x*(2 + x + 3*x^2) / (1 - x)^3. - R. J. Mathar, Oct 15 2008
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MATHEMATICA
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PROG
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CROSSREFS
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KEYWORD
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nonn,less,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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