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!)
A050674 Inserting a digit '0' between adjacent digits of n makes a prime. 22

%I #23 Oct 15 2019 12:02:28

%S 11,13,17,19,37,41,49,53,59,61,67,71,79,89,97,107,109,113,131,133,151,

%T 161,167,179,193,199,211,217,221,247,257,259,277,287,289,293,313,319,

%U 323,337,343,359,373,377,383,389,409,457,469,479,481,493,511,527,553

%N Inserting a digit '0' between adjacent digits of n makes a prime.

%e 373 becomes 3(0)7(0)3 which is prime 30703.

%t (* This program works in Mathematica 6.0 and later *)

%t Select[Range[11, 1000,2], PrimeQ[FromDigits[Riffle[IntegerDigits[#], 0]]] &] (* _T. D. Noe_, Dec 22 2010 *)

%t (* The following program has been tested in Mathematica 5.1 and it works *)

%t Reap[c = 0; d = 0; Do[If[MemberQ[{1, 3, 7, 9}, Mod[n, 10]], id = IntegerDigits[n]; Do[id[[k]] = {id[[k]], d}, {k, Length[id] - 1}]; If[PrimeQ[FromDigits[Flatten[id]]], Sow[n]; c++; If[c > 999, Break[]]]], {n, 11, 20000}]][[2,1]] (* _Zak Seidov_, Dec 22 2010 *)

%Y Cf. A050711, A050712, A050713, A050715, A050716, A050717, A050718, A050719.

%K nonn,base

%O 1,1

%A _Patrick De Geest_, Aug 15 1999

%E Offset set to 1 by _Georg Fischer_, Oct 15 2019

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 April 24 00:30 EDT 2024. Contains 371917 sequences. (Running on oeis4.)