A064118 Numbers k such that the first k digits of e form a prime.

1, 3, 7, 85, 1781, 2780, 112280, 155025

Offset: 1

Author

Shyam Sunder Gupta, Sep 09 2001

Keywords

• base
• more
• nonn

Comments

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

Examples

			a(2)=3 because the 3-digit number 271 is prime.
		

References

• C. A. Pickover, The Mathematics of Oz, "2, 271, 2718281", Chapter 95, Camb.Univ.Press, UK 2002.

Links

• Eric Weisstein's World of Mathematics, Constant Primes
• Eric Weisstein's World of Mathematics, e Digits
• Eric Weisstein's World of Mathematics, e-Prime
• Eric Weisstein's World of Mathematics, Integer Sequence Primes
• Index entries related to "constant primes".

Crossrefs

Cf. A001113.

Cf. A047658.

Programs

Mathematica

Do[If[PrimeQ[FromDigits[RealDigits[N[E, n + 10], 10, n][[1]]]], Print[n]], {n, 1, 2300}]

Extensions

One more term from Robert G. Wilson v, Sep 28 2001

a(6) from Eric W. Weisstein, Jan 17 2005

a(7) from Eric W. Weisstein, Jul 03 2009

a(8) from Eric W. Weisstein, Oct 11 2010