The OEIS is supported by the many generous donors to the OEIS Foundation.

 Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 60th year, we have over 367,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”). Other ways to Give
 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A054256 Concatenation of n in base 2 up to base 10 is prime, all numbers are interpreted as decimals. 3

%I #10 Oct 20 2019 17:27:11

%S 7,33,169,197,209,351,401,419,459,541,553,599,883,971,981,1081,1107,

%T 1201,1351,1363,2011,2321,2347,2563,2607,2679,2703,2861,2869,2909,

%U 2959,3033,3067,3177,3333,3403,3437,3461,3471,3513,3601,3647,3769,3821,3833

%N Concatenation of n in base 2 up to base 10 is prime, all numbers are interpreted as decimals.

%H Harvey P. Dale, <a href="/A054256/b054256.txt">Table of n, a(n) for n = 0..1000</a>

%e a(1)=7 -> 111{2}=21{3}=13{4}=12{5}=11{6}=10{7}=7{8}=7{9}=7{10} -> 1112113121110777 is a prime.

%t Select[Range[4000],PrimeQ[FromDigits[Flatten[Table[IntegerDigits[#,n],{n,2,10}]]]]&] (* _Harvey P. Dale_, Aug 20 2017 *)

%Y Cf. A054257, A054258.

%K nonn,base

%O 0,1

%A _Patrick De Geest_, Feb 15 2000

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

Last modified December 8 03:15 EST 2023. Contains 367662 sequences. (Running on oeis4.)