A010467 - OEIS

A010467

Decimal expansion of square root of 10.

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

(list; constant; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

Continued fraction expansion is 3 followed by {6} repeated. - Harry J. Smith, Jun 02 2009

In 1594, Joseph Scaliger claimed Pi = sqrt(10), but Ludolph van Ceulen immediately knew this to be wrong. - Alonso del Arte, Jan 17 2013

The 7th-century Hindu mathematician Brahmagupta used this constant as value of Pi. - Stefano Spezia, Jul 08 2022

REFERENCES

Petr Beckmann, A History of Pi, 3rd Ed., Boulder, Colorado: The Golem Press (1974): p. 27.

David Wells, The Penguin Dictionary of Curious and Interesting Numbers. Penguin Books, NY, 1986, Revised edition 1987. See p. 55.

LINKS

Harry J. Smith, Table of n, a(n) for n = 1..20000

Josep M. Brunat and Joan-Carles Lario, A problem on concatenated integers, arXiv:2103.05306 [math.NT], 2021. For 1/sqrt(10).

Jason Kimberley, Index of expansions of sqrt(d) in base b.

Robert Nemiroff and Jerry Bonnell, The first 1 million digits of square root of 10.

Robert Nemiroff and Jerry Bonnell, Plouffe's Inverter, The first 1 million digits of square root of 10.

J. J. O'Connor and E. F. Robertson, Ludolph Van Ceulen.

Index entries for algebraic numbers, degree 2

FORMULA

Sqrt(10) = sqrt(1 + i*sqrt(15)) + sqrt(1 - i*sqrt(15)) = sqrt(1/2 + 2*i*sqrt(5)) + sqrt(1/2 - 2*i*sqrt(5)), where i = sqrt(-1). - Bruno Berselli, Nov 20 2012

Equals 1/sqrt(10), with offset 0. - Michel Marcus, Mar 10 2021

Equals 2 + Sum_{k>=1} Lucas(k)*binomial(2*k,k)/8^k. - Amiram Eldar, Jan 17 2022

a(k) = floor(Sum_{n>=1} A005875(n)/exp(Pi*n/(10^((2/3)*k+(1/3))))) mod 10. Will give the k-th decimal digit of sqrt(10). A005875 : number of ways to write n as sum of 3 squares. - Simon Plouffe, Dec 30 2023

EXAMPLE

3.162277660168379331998893544432718533719555139325216826857504852792594...

MATHEMATICA

RealDigits[N[Sqrt[10], 200]] (* Vladimir Joseph Stephan Orlovsky, May 27 2010 *)

PROG

(PARI) default(realprecision, 20080); x=sqrt(10); for (n=1, 20000, d=floor(x); x=(x-d)*10; write("b010467.txt", n, " ", d)); \\ Harry J. Smith, Jun 02 2009

(Magma) SetDefaultRealField(RealField(100)); Sqrt(10); // Vincenzo Librandi, Feb 15 2020

CROSSREFS

Cf. A000032, A040006 (continued fraction).

Sequence in context: A181187 A104573 A327438 * A335320 A182182 A158823

Adjacent sequences: A010464 A010465 A010466 * A010468 A010469 A010470

KEYWORD

nonn,cons

AUTHOR

N. J. A. Sloane

STATUS

approved