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%I #38 Jun 05 2023 03:05:43
%S 1,1,2,2,9,1,8,9,6,7,1,3,3,7,7,0,3,3,9,6,4,8,2,8,6,4,2,9,5,8,1,7,6,1,
%T 5,7,3,5,3,1,4,2,0,7,7,3,8,5,0,3,0,6,3,3,6,3,0,8,3,1,8,1,5,2,0,9,0,1,
%U 7,5,9,3,4,1,4,8,5,7,1,2,7,4,2,6,5,7,4,2,3,1,7,8,6,8,4,2,8,7,1,7,5,3,4,6,3
%N Decimal expansion of 2*exp(-gamma).
%D Steven R. Finch, Mathematical Constants, Cambridge University Press, 2003, Section 2.3, Landau-Ramanujan constant, p. 100.
%H G. C. Greubel, <a href="/A125313/b125313.txt">Table of n, a(n) for n = 1..10000</a>
%H A. Granville, <a href="http://dx.doi.org/10.1080/03461238.1995.10413946">Harald Cramér and the distribution of prime numbers</a>, Scandinavian Actuarial Journal 1: 12-28, (1995) DOI:10.1080/03461238.1995.10413946.
%H Bernard Montaron, <a href="https://arxiv.org/abs/2011.14653">Exponential prime sequences</a>, arXiv:2011.14653 [math.NT], 2020.
%H Simon Plouffe, <a href="http://wayback.cecm.sfu.ca/projects/ISC/ISCmain.html">Plouffe's Inverter</a>.
%H S. K. Wilson and B. R. Duffy, <a href="http://dx.doi.org/10.1007/BF00049245">An asymptotic analysis of small holes in thin fluid layers</a>, Journal of Engineering Mathematics, July 1996, Volume 30, Issue 4, pp 445-457.
%F Equals 2*A080130, 2*A001113^(-A001620) and 2/A073004 = 2/A068985^A001620.
%F Equals A088540 * A088541. - _Jean-François Alcover_, Jun 04 2014
%F Equals exp(A002162 - A001620). - _John W. Nicholson_, Apr 03 2015
%e 1.12291896713377033964828642958176157353142077385030633630831815209...
%t RealDigits[2*Exp[-EulerGamma], 10, 111][[1]]
%o (PARI) default(realprecision, 100); 2*exp(-Euler) \\ _G. C. Greubel_, Sep 05 2018
%o (Magma) R:= RealField(100); 2*Exp(-EulerGamma(R)); // _G. C. Greubel_, Sep 05 2018
%K cons,nonn
%O 1,3
%A _Robert G. Wilson v_, Dec 08 2006
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