login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A228226 Integer lengths of log(2)-primes: numbers n such that the concatenation of the first n decimal digits of log(2) is prime. 1
321, 466, 1271, 15690, 18872, 89973 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

No others <= 90220 - Eric W. Weisstein, Oct 28 2015

LINKS

Table of n, a(n) for n=1..6.

Eric Weisstein's World of Mathematics, Constant Primes

Eric Weisstein's World of Mathematics, Integer Sequence Primes

Eric Weisstein's World of Mathematics, Natural Logarithm of 2 Digits

EXAMPLE

log(2) = 0.6931471805... and the 321-digit number 6931...0641 is the smallest prime in the first digits, so a(1) = 321

CROSSREFS

Cf. A002162 (decimal digits of log(2)).

Sequence in context: A261262 A308527 A268517 * A004927 A074350 A144124

Adjacent sequences:  A228223 A228224 A228225 * A228227 A228228 A228229

KEYWORD

nonn,base,hard

AUTHOR

Eric W. Weisstein, Aug 17 2013

EXTENSIONS

a(6) from Eric W. Weisstein, Oct 28 2015

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified July 21 17:20 EDT 2019. Contains 325198 sequences. (Running on oeis4.)