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

1,1

Links

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

Example

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

Prog

(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

Crossrefs

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

Sequence in context: A159466 A284598 A060591 * A069488 A131648 A355856

Adjacent sequences: A214844 A214845 A214846 * A214848 A214849 A214850

Keyword

nonn,base,less

Author

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

Status

approved