A175215 The smaller member of a twin prime pair in which both primes are emirps.

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

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: A346023 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