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A133275
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Numbers X such that 30*X^2-45 is a square.
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0
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3, 63, 1383, 30363, 666603, 14634903, 321301263, 7053992883, 154866542163, 3400009934703, 74645352021303, 1638797734533963, 35978904807725883, 789897108035435463, 17341757471971854303, 380728767275345359203
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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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 (mathar(AT)strw.leidenuniv.nl), Nov 14 2007
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EXAMPLE
| a(n)=(3/2)*[11+2*sqrt(30)]^n+(1/4)*[11+2*sqrt(30)]^n*sqrt(30)+(3/2)*[11-2*sqrt(30)]^n-(1/4) *sqrt(30)*[11-2*sqrt(30)]^n, with n>=0 [From Paolo P. Lava (paoloplava(AT)gmail.com), Aug 06 2008]
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CROSSREFS
| Sequence in context: A151993 A120053 A139293 * A123687 A159605 A180761
Adjacent sequences: A133272 A133273 A133274 * A133276 A133277 A133278
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KEYWORD
| nonn
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AUTHOR
| Richard Choulet (richardchoulet(AT)yahoo.fr), Oct 16 2007
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EXTENSIONS
| More terms from Paolo P. Lava (paoloplava(AT)gmail.com), Aug 06 2008
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