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A117665
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n times the n-th n-gonal number.
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0
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0, 2, 6, 24, 80, 210, 462, 896, 1584, 2610, 4070, 6072, 8736, 12194, 16590, 22080, 28832, 37026, 46854, 58520, 72240, 88242, 106766, 128064, 152400, 180050, 211302, 246456, 285824, 329730, 378510, 432512, 492096, 557634, 629510, 708120, 793872
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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(n) = n (n + 1) (n^2 - 3 n + 4)/2. - corrected by Eric Rowland, Aug 15 2017
a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5) for n > 4.
G.f.: 2*x*(1 - 2*x + 7*x^2)/(1 - x)^5. (End)
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MATHEMATICA
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LinearRecurrence[{5, -10, 10, -5, 1}, {0, 2, 6, 24, 80}, 50] (* Harvey P. Dale, Jan 02 2020 *)
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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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Luc Stevens (lms022(AT)yahoo.com), Apr 11 2006
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STATUS
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approved
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