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A154355
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25n^2 - 36n + 13.
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6
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13, 2, 41, 130, 269, 458, 697, 986, 1325, 1714, 2153, 2642, 3181, 3770, 4409, 5098, 5837, 6626, 7465, 8354, 9293, 10282, 11321, 12410, 13549, 14738, 15977, 17266, 18605, 19994, 21433, 22922, 24461, 26050, 27689, 29378
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,1
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COMMENTS
| The identity (1250n^2-1800n+649)^2-(25n^2-36n+13)*(250n-180)^2=1 can be written as A154358(n)^2-a(n)*A154360(n)^2=1. See also the third comment in A154357.
Numbers of the form (3n-2)^2+(4n-3)^2. - Bruno Berselli, Dec 12 2011
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LINKS
| Index to sequences with linear recurrences with constant coefficients, signature (3,-3,1).
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FORMULA
| G.f.: -(13-37*x+74*x^2)/(x-1)^3. - R. J. Mathar, Jan 05 2011
a(n) = A007533(n-1), n>0. [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jan 14 2009]
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MATHEMATICA
| Table[25n^2-36n+13, {n, 0, 40}] (* From Harvey P. Dale, Apr 02 2011 *)
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CROSSREFS
| Cf. A154354, A154358 - A154361, A202141.
Sequence in context: A040168 A176593 A031066 * A078421 A185808 A178548
Adjacent sequences: A154352 A154353 A154354 * A154356 A154357 A154358
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KEYWORD
| nonn,easy
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AUTHOR
| Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Jan 07 2009
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EXTENSIONS
| Offset corrected from R. J. Mathar, Jan 05 2011
First comment rewritten from Bruno Berselli, Dec 12 2011
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