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A157855
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103680000n^2 - 46108800n + 5126401.
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3
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62697601, 327628801, 799920001, 1479571201, 2366582401, 3460953601, 4762684801, 6271776001, 7988227201, 9912038401, 12043209601, 14381740801, 16927632001, 19680883201, 22641494401, 25809465601, 29184796801, 32767488001
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OFFSET
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1,1
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COMMENTS
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The identity (103680000*n^2-46108800*n+5126401)^2-(3600*n^2-1601*n +178)*(1728000*n-384240)^2=1 can be written as a(n)^2-A157853(n)*A157854(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*(-62697601-139535998*x-5126401*x^2)/(x-1)^3.
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MATHEMATICA
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LinearRecurrence[{3, -3, 1}, {62697601, 327628801, 799920001}, 40]
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PROG
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(Magma) I:=[62697601, 327628801, 799920001]; [n le 3 select I[n] else 3*Self(n-1)-3*Self(n-2)+1*Self(n-3): n in [1..40]];
(PARI) a(n) = 103680000*n^2 - 46108800*n + 5126401.
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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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