A040080 Continued fraction for sqrt(90).

9, 2, 18, 2, 18, 2, 18, 2, 18, 2, 18, 2, 18, 2, 18, 2, 18, 2, 18, 2, 18, 2, 18, 2, 18, 2, 18, 2, 18, 2, 18, 2, 18, 2, 18, 2, 18, 2, 18, 2, 18, 2, 18, 2, 18, 2, 18, 2, 18, 2, 18, 2, 18, 2, 18, 2, 18, 2, 18, 2, 18, 2, 18, 2, 18, 2

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn
• cofr
• easy

Examples

			9.4868329805051379959966806... = 9 + 1/(2 + 1/(18 + 1/(2 + 1/(18 + ...)))). - _Harry J. Smith_, Jun 11 2009
		

Links

• Harry J. Smith, Table of n, a(n) for n = 0..20000
• G. Xiao, Contfrac
• Index entries for continued fractions for constants
• Index entries for linear recurrences with constant coefficients, signature (0, 1).

Crossrefs

Cf. A010541 Decimal expansion. - Harry J. Smith, Jun 11 2009

Programs

Maple

Digits := 100: convert(evalf(sqrt(N)),confrac,90,'cvgts'):

Mathematica

ContinuedFraction[Sqrt[90],300] (* Vladimir Joseph Stephan Orlovsky, Mar 10 2011 *)
PadRight[{9},120,{18,2}] (* Harvey P. Dale, Jun 13 2017 *)

PARI

{ allocatemem(932245000); default(realprecision, 32000); x=contfrac(sqrt(90)); for (n=0, 20000, write("b040080.txt", n, " ", x[n+1])); } \\ Harry J. Smith, Jun 11 2009

PARI

a(n) = if (!n, 9, if (n % 2, 2, 18)); \\ Michel Marcus, Jan 03 2016