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%I #34 May 19 2021 20:56:28
%S 1,3,7,85,1781,2780,112280,155025
%N Numbers k such that the first k digits of e form a prime.
%C The primes are given in A007512. Sequences A065815, A119344, A136583, A210706,... are analogs for gamma, sqrt(3), sqrt(10), 3^(1/3), .... The MathWorld page about "Constant Primes" lists further examples. - _M. F. Hasler_, Aug 31 2013
%D C. A. Pickover, The Mathematics of Oz, "2, 271, 2718281", Chapter 95, Camb.Univ.Press, UK 2002.
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/ConstantPrimes.html">Constant Primes</a>
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/eDigits.html">e Digits</a>
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/e-Prime.html">e-Prime</a>
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/IntegerSequencePrimes.html">Integer Sequence Primes</a>
%H <a href="/index/Con#constant_primes">Index entries related to "constant primes".</a>
%e a(2)=3 because the 3-digit number 271 is prime.
%t Do[If[PrimeQ[FromDigits[RealDigits[N[E, n + 10], 10, n][[1]]]], Print[n]], {n, 1, 2300}]
%Y Cf. A001113.
%Y Cf. A047658.
%K base,more,nonn
%O 1,2
%A _Shyam Sunder Gupta_, Sep 09 2001
%E One more term from _Robert G. Wilson v_, Sep 28 2001
%E a(6) from _Eric W. Weisstein_, Jan 17 2005
%E a(7) from _Eric W. Weisstein_, Jul 03 2009
%E a(8) from _Eric W. Weisstein_, Oct 11 2010
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