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A158325
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a(n) = 484n^2 + 2n.
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2
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486, 1940, 4362, 7752, 12110, 17436, 23730, 30992, 39222, 48420, 58586, 69720, 81822, 94892, 108930, 123936, 139910, 156852, 174762, 193640, 213486, 234300, 256082, 278832, 302550, 327236, 352890, 379512, 407102, 435660, 465186, 495680
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OFFSET
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1,1
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COMMENTS
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The identity (484*n+1)^2 - (484*n^2 + 2*n)*(22)^2 = 1 can be written as A158326(n)^2 - a(n)*(22)^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*(486+482*x)/(1-x)^3.
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MATHEMATICA
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LinearRecurrence[{3, -3, 1}, {486, 1940, 4362}, 50]
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PROG
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(Magma) I:=[486, 1940, 4362]; [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) = 484*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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