A064118 - OEIS

A064118

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

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

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OFFSET

1,2

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

REFERENCES

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

LINKS

Table of n, a(n) for n=1..8.

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".

EXAMPLE

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

MATHEMATICA

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

CROSSREFS

Cf. A001113.

Cf. A047658.

Sequence in context: A219588 A219375 A326427 * A041705 A137130 A058379

Adjacent sequences: A064115 A064116 A064117 * A064119 A064120 A064121

KEYWORD

base,more,nonn

AUTHOR

Shyam Sunder Gupta, Sep 09 2001

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

STATUS

approved