A210498 Prime numbers that become emirps when their least-significant-digit is deleted.

131, 137, 139, 173, 179, 311, 313, 317, 373, 379, 719, 733, 739, 797, 971, 977, 1493, 1499, 1571, 1579, 1993, 1997, 1999, 3119, 3371, 3373, 3593, 7013, 7019, 7331, 7333, 7393, 7433, 7517, 7691, 7699, 9371, 9377, 9413, 9419, 9533, 9539, 9677, 9679, 9719, 9833

Offset: 1

Author

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

Keywords

• nonn
• base

Comments

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

Examples

			Example: a(1)=131, which becomes 13 upon deletion, which is an emirp.
		

Links

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

Crossrefs

Cf. A006567, A024770, A000040, A225235

Programs

R

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