A214847 Primes that become emirps when their most-significant-digit is deleted.
113, 131, 137, 173, 179, 197, 271, 313, 317, 331, 337, 373, 379, 397, 431, 479, 571, 613, 617, 631, 673, 773, 797, 937, 971, 997, 1013, 1031, 1097, 1709, 1733, 1907, 2017, 2113, 2179, 2311, 2347, 2389, 2953, 2971, 3037, 3079, 3167, 3347, 3359, 3389, 3701, 3709
Offset: 1
Examples
113 and 1013 are both in the sequence, because upon deletion they become 13, which is an emirp.
Links
- Christian N. K. Anderson, Table of n, a(n) for n = 1..10000
Programs
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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(as.bigz(no0(substr((i=nextprime(i)),2,200))))) y[(len=len+1)]=i