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A175633
Numbers x such that x^2 - 28*y^2 = 1 for some integer y.
2
1, 127, 32257, 8193151, 2081028097, 528572943487, 134255446617601, 34100354867927167, 8661355881006882817, 2199950293420880308351, 558778713173022591438337, 141927593195654317345029247
OFFSET
1,2
COMMENTS
This sequence gives the values of x in solutions of the Pell equation x^2 - 28*y^2 = 1; the corresponding y values are in A175672. [Edited by Jon E. Schoenfield, May 04 2014]
FORMULA
a(n) = 254*a(n-1) - a(n-2) (with a(1)=1, a(2)=127).
G.f.: x*(1-127*x)/(1-254*x+x^2). - Bruno Berselli, Apr 18 2011
CROSSREFS
Cf. A175672.
Row 8 of array A188644.
Sequence in context: A069408 A289474 A069434 * A175825 A217914 A203798
KEYWORD
nonn
AUTHOR
Vincenzo Librandi, Dec 04 2010
STATUS
approved