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48, 194, 438, 780, 1220, 1758, 2394, 3128, 3960, 4890, 5918, 7044, 8268, 9590, 11010, 12528, 14144, 15858, 17670, 19580, 21588, 23694, 25898, 28200, 30600, 33098, 35694, 38388, 41180, 44070, 47058, 50144, 53328, 56610, 59990, 63468, 67044
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| The identity (98n-1)^2-(49n^2-n)*14^2=1 can be written as A157924(n)^2-a(n)*14^2=1. - Vincenzo Librandi, Feb 05 2012
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LINKS
| Vincenzo Librandi, Table of n, a(n) for n = 1..10000
E. J. Barbeau, Polynomial Excursions, Chapter 10: Diophantine equations (2010), pages 84-85 (row 14 in the first table at p. 85, case d(t) = t*(7^2*t-1)).
Index to sequences with linear recurrences with constant coefficients, signature (3,-3,1).
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FORMULA
| G.f.: x*(-48-50*x)/(x-1)^3. - Vincenzo Librandi, Feb 05 2012
a(n) = 3*a(n-1) -3*a(n-2) +a(n-3). - Vincenzo Librandi, Feb 05 2012
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MATHEMATICA
| LinearRecurrence[{3, -3, 1}, {48, 194, 438}, 50] (* Vincenzo Librandi, Feb 05 2012
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PROG
| (MAGMA) I:=[48, 194, 438]; [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, Feb 05 2012
(PARI) for(n=1, 40, print1(49*n^2 - n", ")); \\ Vincenzo Librandi, Feb 05 2012
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CROSSREFS
| Cf. A157924.
Sequence in context: A066134 A005911 A130566 * A072254 A183683 A062248
Adjacent sequences: A157920 A157921 A157922 * A157924 A157925 A157926
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KEYWORD
| nonn,easy,changed
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AUTHOR
| Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Mar 09 2009
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