A214847 - OEIS

%I #15 May 06 2013 11:24:06

%S 113,131,137,173,179,197,271,313,317,331,337,373,379,397,431,479,571,

%T 613,617,631,673,773,797,937,971,997,1013,1031,1097,1709,1733,1907,

%U 2017,2113,2179,2311,2347,2389,2953,2971,3037,3079,3167,3347,3359,3389,3701,3709

%N Primes that become emirps when their most-significant-digit is deleted.

%H Christian N. K. Anderson, <a href="/A214847/b214847.txt">Table of n, a(n) for n = 1..10000</a>

%e 113 and 1013 are both in the sequence, because upon deletion they become 13, which is an emirp.

%o (R) library(gmp); isemirp<-function(x) isprime(x) & (j=paste(rev(unlist(strsplit(as.character(x),split=""))),collapse=""))!=x & isprime(j);

%o no0<-function(s){ while(substr(s,1,1)=="0" & nchar(s)>1) s=substr(s,2,nchar(s)); s}

%o i=as.bigz(0); y=as.bigz(rep(0,100)); len=0;

%o while(len<100)

%o if(isemirp(as.bigz(no0(substr((i=nextprime(i)),2,200)))))

%o y[(len=len+1)]=i

%Y Cf. A210498, A006567, A024770, A000040, A225235, A225234.

%K nonn,base,less

%O 1,1

%A _Kevin L. Schwartz_ and _Christian N. K. Anderson_, May 03 2013