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A175215 The smaller member of a twin prime pair in which both primes are emirps. 1
71, 1031, 1151, 1229, 3299, 3371, 3389, 3467, 3851, 7457, 7949, 9011, 9437, 10007, 10067, 10457, 10889, 11159, 11699, 11717, 11777, 11969, 12071, 12107, 13709, 13757, 14447, 14549, 14591, 15731, 16451, 17207, 17681, 17747, 17909, 18911, 19421, 19541 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Subsequence of A001359 and of A006567.

LINKS

Metin Sariyar, Table of n, a(n) for n = 1..16451

Green, Prime Curios, Entry 71

Carlos Rivera, Puzzle 973. Largest known twin & emirp, The Prime Puzzles & Problems Connection.

MAPLE

read("transforms") ; isA001359 := proc(n) isprime(n) and isprime(n+2) ; end proc:

isA006567 := proc(n) local r ; r := digrev(n) ; isprime(n) and isprime(r) and n<> r ; end proc:

isA175215 := proc(n) isA001359(n) and isA006567(n) and isA006567(n+2) ; end proc:

for i from 1 to 10000 do p := ithprime(i) ; if isA175215(p) then printf("%d, ", p) ; end if; end do: # R. J. Mathar, Mar 16 2010

MATHEMATICA

Do[IR=IntegerReverse; Q=PrimeQ; If[Q[n]&&Q[n+2]&&Q[IR[n]]&&PrimeQ[IR[n+2]]&&!n==IR[n]&&!(n+2)==IR[n+2], Print[n]], {n, 5, 10^5, 6}] (* Metin Sariyar, Dec 17 2019 *)

PROG

(MAGMA) emirp:=func<n|IsPrime(n) and IsPrime(Seqint(Reverse(Intseq(n)))) and Intseq(n) ne Reverse(Intseq(n))>; [p:p in PrimesUpTo(20000)| emirp(p) and emirp(p+2)]; // Marius A. Burtea, Dec 17 2019

CROSSREFS

Cf. A001359, A006567.

Sequence in context: A210699 A050885 A200909 * A231414 A071827 A289899

Adjacent sequences:  A175212 A175213 A175214 * A175216 A175217 A175218

KEYWORD

nonn,base

AUTHOR

Lekraj Beedassy, Mar 06 2010

EXTENSIONS

11699 inserted, 14921 -> 19421 corrected by R. J. Mathar, Mar 16 2010

STATUS

approved

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Last modified February 24 22:57 EST 2020. Contains 332216 sequences. (Running on oeis4.)