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223, 896, 2019, 3592, 5615, 8088, 11011, 14384, 18207, 22480, 27203, 32376, 37999, 44072, 50595, 57568, 64991, 72864, 81187, 89960, 99183, 108856, 118979, 129552, 140575, 152048, 163971, 176344, 189167, 202440, 216163, 230336, 244959, 260032
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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 A158227(n)^2-a(n)*(15)^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*(-223-227*x)/(x-1)^3.
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MATHEMATICA
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LinearRecurrence[{3, -3, 1}, {223, 896, 2019}, 50]
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PROG
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(Magma) I:=[223, 896, 2019]; [n le 3 select I[n] else 3*Self(n-1)-3*Self(n-2)+1*Self(n-3): n in [1..50]];
(PARI) a(n) = 225*n^2 - 2*n.
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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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