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A156843
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279841n^2 - 165048n + 24335.
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4
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24335, 139128, 813603, 2047760, 3841599, 6195120, 9108323, 12581208, 16613775, 21206024, 26357955, 32069568, 38340863, 45171840, 52562499, 60512840, 69022863, 78092568, 87721955, 97911024, 108659775, 119968208, 131836323
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OFFSET
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0,1
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COMMENTS
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The identity (279841*n^2-165048*n+24335)^2-(529*n^2-312*n+46)*(12167*n-3588)^2=1 can be written as a(n)^2-A156841(n)*A156846(n)^2=1 for n>0.
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LINKS
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FORMULA
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a(n) = 3*a(n-1) -3*a(n-2) +a(n-3).
G.f.: (24335+66123*x+469224*x^2)/(1-x)^3.
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MATHEMATICA
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LinearRecurrence[{3, -3, 1}, {24335, 139128, 813603}, 40]
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PROG
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(Magma) I:=[24335, 139128, 813603]; [n le 3 select I[n] else 3*Self(n-1)-3*Self(n-2)+1*Self(n-3): n in [1..40]];
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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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