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A133275 Numbers X such that 30*X^2-45 is a square. 2
3, 63, 1383, 30363, 666603, 14634903, 321301263, 7053992883, 154866542163, 3400009934703, 74645352021303, 1638797734533963, 35978904807725883, 789897108035435463, 17341757471971854303, 380728767275345359203 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Positive values of x (or y) satisfying x^2 - 22xy + y^2 + 180 = 0. - Colin Barker, Feb 19 2014
LINKS
FORMULA
a(n+2) = 22*a(n+1)-a(n).
a(n+1) = 11*a(n)+2*(30*a(n)^2-45)^0.5.
G.f.: -3*x*(-1+x)/(1-22*x+x^2). - R. J. Mathar, Nov 14 2007
a(n) = 3*A157014(n). - Colin Barker, Feb 19 2014
MATHEMATICA
CoefficientList[Series[3 (1 - x)/(1 - 22 x + x^2), {x, 0, 40}], x] (* Vincenzo Librandi, Feb 21 2014 *)
PROG
(Magma) I:=[3, 63]; [n le 2 select I[n] else 22*Self(n-1)-Self(n-2): n in [1..20]]; // Vincenzo Librandi, Feb 21 2014
CROSSREFS
Cf. A157014.
Sequence in context: A120053 A139293 A370827 * A258657 A331012 A369955
KEYWORD
nonn,easy
AUTHOR
Richard Choulet, Oct 16 2007
EXTENSIONS
More terms from Paolo P. Lava, Aug 06 2008
STATUS
approved

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Last modified July 19 16:24 EDT 2024. Contains 374410 sequences. (Running on oeis4.)