This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A213610 #31 Nov 25 2023 11:54:27 %S A213610 3,7,6,7,3,0,3,1,3,4,6,1,7,7,0,6,5,5,4,6,8,1,9,8,4,0,0,4,2,0,3,1,9,3, %T A213610 0,8,2,6,8,6,2,3,5,0,8,3,5,2,4,1,8,6,5,5,2,3,2,0,7,4,6,3,8,2,9,6,7,0, %U A213610 7,2,6,9,2,2,1,3,0,7,6,9,8,8,8,0,1,6,6,8,7,5,1,9,9,5,6,5,5,8,6,6,9,3,6,4,8 %N A213610 Decimal expansion of the characteristic impedance of vacuum in SI units as defined before 20 May 2019. %C A213610 Denoted Z_0, this is a function of assigned metrological constants. Regarding these, see A003678 for general context notes, references and links. - _Stanislav Sykora_, Jun 16 2012 %H A213610 Wikipedia, <a href="https://en.wikipedia.org/wiki/Impedance_of_free_space">Impedance of free space</a> %F A213610 Z_0 = [magnetic_permeability_of_vacuum]*[speed_of_light_in_vacuum] = 10^-6 * A019694 * A003678 = Pi * 119.9169832 Ohms, where 119.9169832 = 4*10^-7 * 299792458 (exact value). [The 2nd equality is valid only for the SI definition that was in effect until 2019.] %F A213610 Equals 2*alpha*h/e^2, where alpha is the fine-structure constant, h is the Planck constant and e is the elementary charge. The decimal expansion of Z_0 in SI units after the redefinition in 2019 is 2*A003673*A003676/A081823^2. - _Jianing Song_, Nov 25 2023 %e A213610 376.730313 ... Ohm [also kg * m^2 * s^-3 * A^-2]. %t A213610 RealDigits[4*Pi*10^-7*299792458, 10, 105] // First (* _Jean-François Alcover_, Mar 07 2014 *) %Y A213610 Cf. A003673, A003676, A081823. %Y A213610 Other assigned constants: A003678, A182999, A081799, A019694, A072915, A213611, A213612, A213613, A213614. %K A213610 nonn,cons %O A213610 3,1 %A A213610 _Stanislav Sykora_, Jun 16 2012 %E A213610 Edited by _Andrey Zabolotskiy_, Aug 12 2020