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A257954
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Heptagonal numbers (A000566) that are the sum of seven consecutive heptagonal numbers.
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2
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380300389, 13416840252277, 102114787991863121805337, 3602567760523753992917728705, 27418932936218445934971843788960252365, 967328687318574474761362987583880892300813, 7362282174260114825535960626325353709734456640627073
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OFFSET
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1,1
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LINKS
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FORMULA
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a(n) = a(n-1)+268510893235202*a(n-2)-268510893235202*a(n-3)-a(n-4)+a(n-5).
G.f.: -7*x*(847*x^4 +29708856*x^3 -1309948358220074*x^2 +1916637135984*x +54328627) / ((x -1)*(x^2 -16386302*x +1)*(x^2 +16386302*x +1)).
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EXAMPLE
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380300389 is in the sequence because H(12334) = 380300389 = 54258714 + 54282010 + 54305311 + 54328617 + 54351928 + 54375244 + 54398565 = H(4659)+...+H(4665).
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PROG
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(PARI) Vec(-7*x*(847*x^4 +29708856*x^3 -1309948358220074*x^2 +1916637135984*x +54328627) / ((x -1)*(x^2 -16386302*x +1)*(x^2 +16386302*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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