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A154517
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a(n) = 9*n^2 + n.
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5
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10, 38, 84, 148, 230, 330, 448, 584, 738, 910, 1100, 1308, 1534, 1778, 2040, 2320, 2618, 2934, 3268, 3620, 3990, 4378, 4784, 5208, 5650, 6110, 6588, 7084, 7598, 8130, 8680, 9248, 9834, 10438, 11060, 11700, 12358, 13034, 13728, 14440
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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 - a(n)*A154519(n)^2 = 1 (see also the second comment at A154515). - Vincenzo Librandi, Jan 31 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:=[10, 38, 84]; [n le 3 select I[n] else 3*Self(n-1)-3*Self(n-2)+1*Self(n-3): n in [1..50]]; // Vincenzo Librandi, Jan 31 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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