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A225235 Emirps whose internal digits are also an emirp. 4
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

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

LINKS

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

EXAMPLE

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.

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((i=nextprime(i)))) if(isemirp(as.bigz(no0(substr(i, 2, nchar(as.character(i))-1))))) y[(len=len+1)]=i;

as.vector(y)

CROSSREFS

Cf. A210498, A006567, A069686, A210498.

Sequence in context: A210160 A234179 A108510 * A289907 A125490 A237334

Adjacent sequences:  A225232 A225233 A225234 * A225236 A225237 A225238

KEYWORD

nonn,base,less

AUTHOR

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

STATUS

approved

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Last modified November 12 16:50 EST 2018. Contains 317116 sequences. (Running on oeis4.)