A007512 Primes of the form floor(e*10^k), i.e., formed by concatenation of an initial segment of the decimal expansion of e.

2, 271, 2718281, 2718281828459045235360287471352662497757247093699959574966967627724076630353547594571

Offset: 1

Author

N. J. A. Sloane, Robert G. Wilson v, Simon Plouffe

Keywords

• base
• nonn

Comments

The number of digits in a(n) is given in A064118. This allows us to get larger terms that cannot be displayed here, via the given FORMULA. Sequences A005042, A072952, A115453, A119343, A210704, ... are the analogs for Pi, gamma, sqrt(2), sqrt(3), 3^(1/3), ... - M. F. Hasler, Aug 31 2013

References

• N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

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

Programs

Maple

Digits := 110; n0 := evalf(E); for i from 1 to 100 do t1 := trunc(10^i*n0); if isprime(t1) then print(t1); fi; od:

PARI

c=exp(1);for(k=0,precision(c),ispseudoprime(c\.1^k) & print1(c\.1^k,",")) \\ M. F. Hasler, Sep 01 2013

Formula

a(n) = floor(e*10^(A064118(n)-1)). - M. F. Hasler, Aug 31 2013

Extensions

Next term is a 1781-digit BPSW-probable prime 2718281828459045235...211151368350627526023. - Randall L Rathbun, Feb 02 2002

Edited by T. D. Noe, Oct 30 2008

Edited by M. F. Hasler, Aug 31 2013