A248249 -id:A248249 - cp's OEIS frontend

A010477 Decimal expansion of square root of 21.

4, 5, 8, 2, 5, 7, 5, 6, 9, 4, 9, 5, 5, 8, 4, 0, 0, 0, 6, 5, 8, 8, 0, 4, 7, 1, 9, 3, 7, 2, 8, 0, 0, 8, 4, 8, 8, 9, 8, 4, 4, 5, 6, 5, 7, 6, 7, 6, 7, 9, 7, 1, 9, 0, 2, 6, 0, 7, 2, 4, 2, 1, 2, 3, 9, 0, 6, 8, 6, 8, 4, 2, 5, 5, 4, 7, 7, 7, 0, 8, 8, 6, 6, 0, 4, 3, 6, 1, 5, 5, 9, 4, 9, 3, 4, 4, 5, 0, 3

Offset: 1

N. J. A. Sloane

Continued fraction expansion is 4 followed by {1, 1, 2, 1, 1, 8} repeated. - Harry J. Smith, Jun 03 2009

The fundamntal algebraic (integer) number in the field Q(sqrt(21)) is (1 + sqrt(21))/2 = A222134. - Wolfdieter Lang, Nov 21 2023

			4.582575694955840006588047193728008488984456576767971902607242123906868...

Harry J. Smith, Table of n, a(n) for n = 1..20000
Frankfurter Allgemeine Zeitung, Feb 09 2011 (in German)
Index entries for algebraic numbers, degree 2

Cf. A010125 (continued fraction), A248249 (Egyptian fraction).

Cf. A020778 (reciprocal), A222134.

RealDigits[N[Sqrt[21],200]][[1]] (* Vladimir Joseph Stephan Orlovsky, Feb 22 2011 *)

default(realprecision, 20080); x=sqrt(21); for (n=1, 20000, d=floor(x); x=(x-d)*10; write("b010477.txt", n, " ", d));  \\ Harry J. Smith, Jun 03 2009

cp's OEIS Frontend

A010477 Decimal expansion of square root of 21.

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