A225235 Emirps whose internal digits are also an emirp.

1979, 3319, 3371, 3373, 3719, 3733, 7177, 7717, 9133, 9173, 9791, 10177, 10711, 10739, 11071, 11497, 11579, 11677, 13477, 13591, 13597, 17011, 17393, 17519, 19531, 19913, 30139, 30319, 30971, 31139, 31799, 31991, 37619, 39371, 39419, 39839, 70313, 70373, 70717

Offset: 1

Author

Kevin L. Schwartz and Christian N. K. Anderson, May 03 2013

Keywords

• nonn
• base
• less

Comments

This sequence (like the emirps) experiences large gaps when the most-significant-digit is {2,4,5,6,8}.

Examples

			7177 and 10177 are in the sequence because both are emirps, and both become the emirp 17 upon deletion of their first and last digits.
		

Links

• Christian N. K. Anderson, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A210498, A006567, A069686, A210498.

Programs

R

library(gmp); isemirp<-function(x) isprime(x) & (j=paste(rev(unlist(strsplit(as.character(x), split=""))), collapse=""))!=x & isprime(j);
no0<-function(s){ while(substr(s,1,1)=="0" & nchar(s)>1) s=substr(s,2,nchar(s)); s};
i=as.bigz(0); y=as.bigz(rep(0, 100)); len=0;
while(len<100) if(isemirp((i=nextprime(i)))) if(isemirp(as.bigz(no0(substr(i,2,nchar(as.character(i))-1))))) y[(len=len+1)]=i;
as.vector(y)