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A132593 Sequence allows us to find X values of the equation: X(X + 1) - 10*Y^2 = 0. 1
0, 9, 360, 13689, 519840, 19740249, 749609640, 28465426089, 1080936581760, 41047124680809, 1558709801289000, 59189925324301209, 2247658452522156960, 85351831270517663289, 3241121929827149048040, 123077281502161146162249 (list; graph; refs; listen; history; internal format)
OFFSET

0,2

FORMULA

a(0)=0, a(1)=9 and a(n)=38*a(n-1) - a(n-2) + 18.

a(n)=-1/2+(1/4)*[19-6*sqrt(10)]^n+(1/4)*[19+6*sqrt(10)]^n, with n>=0 - Paolo P. Lava (paoloplava(AT)gmail.com), Jul 11 2008

a(n) = (A078986(n) - 1)/2 [From Max Alekseyev (maxale(AT)gmail.com), Nov 13 2009]

CROSSREFS

Cf. A007654.

Sequence in context: A119756 A063068 A130558 * A162133 A197179 A195888

Adjacent sequences:  A132590 A132591 A132592 * A132594 A132595 A132596

KEYWORD

nonn

AUTHOR

Mohamed Bouhamida (bhmd95(AT)yahoo.fr), Nov 14 2007

EXTENSIONS

More terms from Max Alekseyev (maxale(AT)gmail.com), Nov 13 2009

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Last modified February 15 15:20 EST 2012. Contains 205823 sequences.