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

Author

Lekraj Beedassy, Mar 06 2010

Keywords

• nonn
• base

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.

Crossrefs

Cf. A001359, A006567.

Programs

Magma

emirp:=func; [p:p in PrimesUpTo(20000)| emirp(p) and emirp(p+2)]; // Marius A. Burtea, Dec 17 2019

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 *)

Extensions

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