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A125200
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a(n) = n*(4*n^2 + n - 1)/2.
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3
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2, 17, 57, 134, 260, 447, 707, 1052, 1494, 2045, 2717, 3522, 4472, 5579, 6855, 8312, 9962, 11817, 13889, 16190, 18732, 21527, 24587, 27924, 31550, 35477, 39717, 44282, 49184, 54435, 60047, 66032, 72402, 79169, 86345, 93942, 101972, 110447, 119379
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OFFSET
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1,1
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COMMENTS
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a(n) = Sum_{k=1..n} (4*n*k - n - k), sums of rows of the triangle in A125199.
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LINKS
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FORMULA
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a(n) = 4*a(n-1) -6*a(n-2) +4*a(n-3) -a(n-4). - R. J. Mathar, Feb 12 2010
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MATHEMATICA
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LinearRecurrence[{4, -6, 4, -1}, {2, 17, 57, 134}, 40] (* Harvey P. Dale, Feb 05 2013 *)
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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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