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A158592
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a(n)=19*(19*n^2+1).
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1
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19, 380, 1463, 3268, 5795, 9044, 13015, 17708, 23123, 29260, 36119, 43700, 52003, 61028, 70775, 81244, 92435, 104348, 116983, 130340, 144419, 159220, 174743, 190988, 207955, 225644, 244055, 263188, 283043, 303620, 324919, 346940, 369683
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,1
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COMMENTS
| The identity (38*n^2+1)^2 - (361*n^2+19)*(2*n)^2 = 1 can be written in
Pell-format as (A158593(n))^2 - a(n)* (A005843(n))^2 =1.
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LINKS
| Vincenzo Librandi, X^2-AY^2=1
Edward Everett Withford, Pell Equation
Wolfram MathWorld, Pell Equation
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FORMULA
| a(n)= 3*a(n-1) -3*a(n-2) +a(n-3). G.f.: -19*(1+17*x+20*x^2)/(x-1)^3.
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CROSSREFS
| Sequence in context: A041686 A023283 A075839 * A072359 A094737 A009075
Adjacent sequences: A158589 A158590 A158591 * A158593 A158594 A158595
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KEYWORD
| nonn,easy
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AUTHOR
| Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Mar 22 2009
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EXTENSIONS
| Comment rewritten, formula replaced by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 28 2009
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