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

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A155032 Primes p such that the concatenation of pi(p) and p is prime, where pi is the prime counting function. 1

%I #9 Feb 16 2021 01:02:36

%S 3,59,83,179,283,353,431,709,1433,2269,2381,3559,3593,4153,5503,6899,

%T 7109,7351,7649,8513,11909,13297,14107,14437,14591,16073,16127,16451,

%U 16901,17117,17539,17987,18149,19777,20759,21317,22027,24439,25357,26783,27437,29269,30253,32299,34057,34259,34421,34543,35617,36307,37049

%N Primes p such that the concatenation of pi(p) and p is prime, where pi is the prime counting function.

%e Since 3 is the second prime number and the concatenation of 2 and 3 gives 23, which is prime, 3 is in the sequence.

%e Since 59 is the seventeenth prime and the concatenation of 17 and 59 gives 1759, another prime, 59 is also in the sequence.

%t (* First run the program given for A154963 *) Prime[A154963]

%Y pi(a(n)) = A154963(n).

%K nonn,base

%O 1,1

%A _Juri-Stepan Gerasimov_, Jan 19 2009

%E Edited and extended beyond a(3) by _Alonso del Arte_, Jan 20 2009, with thanks to _Klaus Brockhaus_'s edit of A154963

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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 28 05:02 EDT 2024. Contains 371235 sequences. (Running on oeis4.)