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A210498 Prime numbers that become emirps when their least-significant-digit is deleted. 4
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 (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

Example: a(1)=131, which becomes 13 upon deletion, 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); 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

CROSSREFS

Cf. A006567, A024770, A000040, A225235

Sequence in context: A001331 A291620 A145096 * A050671 A095317 A084549

Adjacent sequences:  A210495 A210496 A210497 * A210499 A210500 A210501

KEYWORD

nonn,base

AUTHOR

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

STATUS

approved

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Last modified March 26 12:43 EDT 2019. Contains 321497 sequences. (Running on oeis4.)