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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A155032 Primes n such that concatenation of pi(n) and n is prime, with pi being the prime counting function. 1
3, 59, 83, 179, 283, 353, 431, 709, 1433, 2269, 2381, 3559, 3593, 4153, 5503, 6899, 7109, 7351, 7649, 8513, 11909, 13297, 14107, 14437, 14591, 16073, 16127, 16451, 16901, 17117, 17539, 17987, 18149, 19777, 20759, 21317, 22027, 24439, 25357, 26783, 27437, 29269, 30253, 32299, 34057, 34259, 34421, 34543, 35617, 36307, 37049 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..51.

EXAMPLE

Since 3 is the second prime number and the concatenation of 2 and 3 gives 23, which is prime, 3 is in the sequence. Since 59 is the seventeenth prime and the concatenation of 17 and 59 gives 1759, another prime, 59 is also in the sequence.

MATHEMATICA

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

CROSSREFS

pi(a(n)) = A154963.

Sequence in context: A100611 A139882 A139874 * A107212 A002148 A200957

Adjacent sequences:  A155029 A155030 A155031 * A155033 A155034 A155035

KEYWORD

nonn,base

AUTHOR

Juri-Stepan Gerasimov, Jan 19 2009

EXTENSIONS

Edited and extended beyond a(3) by Alonso del Arte, Jan 20 2009, with thanks to Klaus Brockhaus's edit of A154963

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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified March 27 22:02 EDT 2017. Contains 284182 sequences.