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A259162
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Positive hexagonal numbers (A000384) that are pentagonal numbers (A000326) divided by 2.
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3
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6, 58311, 559902916, 5376187741821, 51622154137063026, 495675918647891434531, 4759480119234899417304336, 45700527609217585557064800441, 438816461344227137284036796530846, 4213515616126741362983735763224383551, 40458176507232509223142693514443734326556
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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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G.f.: -x*(x^2+693*x+6) / ((x-1)*(x^2-9602*x+1)).
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EXAMPLE
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6 is in the sequence because 6 is the 2nd hexagonal number, and 2*6 is the 3rd pentagonal number.
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MATHEMATICA
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LinearRecurrence[{9603, -9603, 1}, {6, 58311, 559902916}, 20] (* Vincenzo Librandi, Jun 20 2015 *)
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PROG
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(PARI) Vec(-x*(x^2+693*x+6)/((x-1)*(x^2-9602*x+1)) + O(x^20))
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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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STATUS
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approved
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