This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A241212 Primes p with an even number of digits such that each digit in the second half of p is larger by 1 than the corresponding digit in the first half. 1

%I

%S 23,67,89,1021,1223,1627,3041,4051,4253,4657,5869,7283,7687,8293,

%T 106217,110221,112223,128239,130241,136247,158269,172283,178289,

%U 188299,208319,226337,230341,250361,272383,286397,320431,322433,326437,328439,338449,340451

%N Primes p with an even number of digits such that each digit in the second half of p is larger by 1 than the corresponding digit in the first half.

%H Robert Israel, <a href="/A241212/b241212.txt">Table of n, a(n) for n = 1..10000</a>

%e E.g., for 2 digit primes: (3, 7, 9) = (2, 6, 8) + 1.

%p N:= 1000; # to get the first N entries

%p A241212[1]:= 23:

%p A241212[2]:= 67:

%p A241212[3]:= 89:

%p count:= 3:

%p for n from 2 while count < N do

%p for x1 from 10^(n-1) to 9*10^(n-1)-2 by 2 while count < N do

%p L:= convert(x1,base,10);

%p if has(L,9) then next fi;

%p x:= 10^n*x1 + x1 + (10^n - 1)/9;

%p if isprime(x) then

%p count:= count+1;

%p A241212[count]:= x

%p fi;

%p od

%p od: # _Robert Israel_, Apr 18 2014

%K nonn,base

%O 1,1

%A _Zak Seidov_, Apr 17 2014

%E Incorrect cross-reference deleted by _Robert Israel_, Apr 18 2014

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.

Last modified June 25 12:55 EDT 2019. Contains 324352 sequences. (Running on oeis4.)