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A173308
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a(n) = 17*n*(n+1).
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1
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0, 34, 102, 204, 340, 510, 714, 952, 1224, 1530, 1870, 2244, 2652, 3094, 3570, 4080, 4624, 5202, 5814, 6460, 7140, 7854, 8602, 9384, 10200, 11050, 11934, 12852, 13804, 14790, 15810, 16864, 17952, 19074, 20230, 21420, 22644, 23902, 25194, 26520, 27880, 29274
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OFFSET
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0,2
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LINKS
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FORMULA
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a(0)=0, a(1)=34, a(2)=102, a(n) = 3*a(n-1)-3*a(n-2)+a(n-3). G.f.: 34*x/(1-x)^3. - Colin Barker, Jan 25 2012
Sum_{n>=1} 1/a(n) = 1/17.
Sum_{n>=1} (-1)^(n+1)/a(n) = (2*log(2) - 1)/17.
Product_{n>=1} (1 - 1/a(n)) = -(17/Pi)*cos(sqrt(21/17)*Pi/2).
Product_{n>=1} (1 + 1/a(n)) = (17/Pi)*cos(sqrt(13/17)*Pi/2). (End)
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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,easy
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AUTHOR
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EXTENSIONS
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Incorrect formulas and examples deleted by R. J. Mathar, Jan 04 2011
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STATUS
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approved
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