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A175215
The smaller member of a twin prime pair in which both primes are emirps.
2
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
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
Sequence in context: A346023 A050885 A200909 * A231414 A071827 A289899
KEYWORD
nonn,base
AUTHOR
Lekraj Beedassy, Mar 06 2010
EXTENSIONS
11699 inserted, 14921 -> 19421 corrected by R. J. Mathar, Mar 16 2010
STATUS
approved