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A041760
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Numerators of continued fraction convergents to sqrt(401).
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1
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20, 801, 32060, 1283201, 51360100, 2055687201, 82278848140, 3293209612801, 131810663360180, 5275719744020001, 211160600424160220, 8451699736710428801, 338279150068841312260, 13539617702490362919201, 541922987249683358080300
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,1
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LINKS
| Tanya Khovanova, Recursive Sequences
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FORMULA
| a(n)=40*a(n-1)+a(n-2), n>1 ; a(0)=20, a(1)=801 . G.f.: (20+x)/(1-40*x-x^2). [From Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Nov 23 2008]
a(n)=(1/2)*sqrt(401)*{[20+sqrt(401)]^n-[20-sqrt(401)]^n}+10*{[20-sqrt(401)]^n+[20+sqrt(401)]^n}, with n>=0 [From Paolo P. Lava (paoloplava(AT)gmail.com), Nov 28 2008]
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CROSSREFS
| Cf. A041761.
Sequence in context: A049214 A002455 A041763 * A117798 A006424 A113102
Adjacent sequences: A041757 A041758 A041759 * A041761 A041762 A041763
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KEYWORD
| nonn,cofr,easy,less
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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