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A157510
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a(n) = 1000*n + 20.
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3
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1020, 2020, 3020, 4020, 5020, 6020, 7020, 8020, 9020, 10020, 11020, 12020, 13020, 14020, 15020, 16020, 17020, 18020, 19020, 20020, 21020, 22020, 23020, 24020, 25020, 26020, 27020, 28020, 29020, 30020, 31020, 32020, 33020, 34020, 35020
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OFFSET
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1,1
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COMMENTS
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The identity (5000*n^2 + 200*n + 1)^2 - (25*n^2 + n)*(1000*n + 20)^2 = 1 can be written as A157511(n)^2 - A173089(n)*a(n)^2 = 1 (see also second part of the comment at A173089). - Vincenzo Librandi, Feb 04 2012
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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:=[1020, 2020]; [n le 2 select I[n] else 2*Self(n-1)-Self(n-2): n in [1..50]]; // Vincenzo Librandi, Feb 04 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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