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A154519
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a(n) = 216*n + 12.
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3
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228, 444, 660, 876, 1092, 1308, 1524, 1740, 1956, 2172, 2388, 2604, 2820, 3036, 3252, 3468, 3684, 3900, 4116, 4332, 4548, 4764, 4980, 5196, 5412, 5628, 5844, 6060, 6276, 6492, 6708, 6924, 7140, 7356, 7572, 7788, 8004, 8220, 8436, 8652
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OFFSET
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1,1
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COMMENTS
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The identity (648*n^2 + 72*n + 1)^2 - (9*n^2 + n)*(216*n + 12)^2 = 1 can be written as A154515(n)^2 - A154517(n)*a(n)^2 = 1 (see also the second comment at A154515).
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LINKS
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FORMULA
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MATHEMATICA
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PROG
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(Magma) I:=[228, 444]; [n le 2 select I[n] else 2*Self(n-1)-Self(n-2): n in [1..50]]; // Vincenzo Librandi, Jan 30 2012
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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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