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A040399 Continued fraction for sqrt(420). 1
20, 2, 40, 2, 40, 2, 40, 2, 40, 2, 40, 2, 40, 2, 40, 2, 40, 2, 40, 2, 40, 2, 40, 2, 40, 2, 40, 2, 40, 2, 40, 2, 40, 2, 40, 2, 40, 2, 40, 2, 40, 2, 40, 2, 40, 2, 40, 2, 40, 2, 40, 2, 40, 2, 40, 2, 40, 2, 40, 2, 40, 2, 40, 2, 40, 2, 40, 2, 40, 2, 40, 2, 40, 2, 40 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Table of n, a(n) for n=0..74.

Index entries for continued fractions for constants

Index entries for linear recurrences with constant coefficients, signature (0, 1).

FORMULA

a(n)=21+19*(-1)^n-20*[C(2*n,n) mod 2], with n>=0 [From Paolo P. Lava, Apr 30 2009]

MAPLE

with(numtheory): Digits := 300: convert(evalf(sqrt(420)), confrac);

CROSSREFS

Sequence in context: A303847 A303849 A277981 * A040390 A040391 A255860

Adjacent sequences:  A040396 A040397 A040398 * A040400 A040401 A040402

KEYWORD

nonn,cofr,easy

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified February 21 23:29 EST 2019. Contains 320381 sequences. (Running on oeis4.)