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A156844
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279841n^2 - 394634n + 139128.
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4
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24335, 469224, 1473795, 3038048, 5161983, 7845600, 11088899, 14891880, 19254543, 24176888, 29658915, 35700624, 42302015, 49463088, 57183843, 65464280, 74304399, 83704200, 93663683, 104182848, 115261695, 126900224
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OFFSET
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1,1
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COMMENTS
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The identity (279841*n^2-394634*n+139128)^2-(529*n^2-746*n+263)*(12167*n-8579)^2=1 can be written as a(n)^2-A156842(n)*A156845(n)^2=1.
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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.: x*(-24335-396219*x-139128*x^2)/(x-1)^3.
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MATHEMATICA
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LinearRecurrence[{3, -3, 1}, {24335, 469224, 1473795}, 40]
Table[279841n^2-394634n+139128, {n, 30}] (* Harvey P. Dale, Mar 02 2021 *)
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PROG
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(Magma) I:=[24335, 469224, 1473795]; [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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