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201, 401, 601, 801, 1001, 1201, 1401, 1601, 1801, 2001, 2201, 2401, 2601, 2801, 3001, 3201, 3401, 3601, 3801, 4001, 4201, 4401, 4601, 4801, 5001, 5201, 5401, 5601, 5801, 6001, 6201, 6401, 6601, 6801, 7001, 7201, 7401, 7601, 7801, 8001, 8201, 8401, 8601
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| The identity (200n+1)^2-(100n^2+n)*20^2=1 can be written as a(n)^2-A055438(n)*20^2=1. - Vincenzo Librandi, Feb 04 2012
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LINKS
| Vincenzo Librandi, Table of n, a(n) for n = 1..10000
Vincenzo Librandi, X^2-AY^2=1
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*(10^2*t+1)).
Index to sequences with linear recurrences with constant coefficients, signature (2,-1).
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FORMULA
| G.f.: x*(201-x)/(1-x)^2. - Vincenzo Librandi, Feb 04 2012
a(n) = 2*a(n-1)-a(n-2). - Vincenzo Librandi, Feb 04 2012
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MATHEMATICA
| 200Range[50]+1 (* From Harvey P. Dale, Feb 24 2011 *)
LinearRecurrence[{2, -1}, {201, 401}, 50] (* Vincenzo Librandi, Feb 04 2012 *)
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PROG
| MAGMA) I:=[201, 401]; [n le 2 select I[n] else 2*Self(n-1)-Self(n-2): n in [1..50]]; // Vincenzo Librandi, Feb 04 2012
(PARI) for(n=1, 50, print1(200*n + 1", ")); \\ Vincenzo Librandi, Feb 04 2012
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CROSSREFS
| Cf. A055438.
Sequence in context: A098963 A107843 A076192 * A202771 A183350 A061697
Adjacent sequences: A157953 A157954 A157955 * A157957 A157958 A157959
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KEYWORD
| nonn,easy,changed
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AUTHOR
| Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Mar 10 2009
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