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A158227
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a(n) = 225*n - 1.
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2
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224, 449, 674, 899, 1124, 1349, 1574, 1799, 2024, 2249, 2474, 2699, 2924, 3149, 3374, 3599, 3824, 4049, 4274, 4499, 4724, 4949, 5174, 5399, 5624, 5849, 6074, 6299, 6524, 6749, 6974, 7199, 7424, 7649, 7874, 8099, 8324, 8549, 8774, 8999, 9224, 9449, 9674
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OFFSET
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1,1
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COMMENTS
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The identity (225*n-1)^2-(225*n^2-2*n)*(15)^2=1 can be written as a(n)^2-A158226(n)*(15)^2=1.
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LINKS
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FORMULA
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a(n) = 2*a(n-1)-a(n-2).
G.f.: x*(224+x)/(1-x)^2.
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MATHEMATICA
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LinearRecurrence[{2, -1}, {224, 449}, 50]
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PROG
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(Magma) I:=[224, 449]; [n le 2 select I[n] else 2*Self(n-1)-Self(n-2): n in [1..50]];
(PARI) a(n) = 225*n - 1.
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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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