A133753 - OEIS

%I #11 Sep 15 2024 16:35:48

%S 73,733,3733,7253,7523,7757,33223,35323,72253,72353,73327,73523,73553,

%T 75223,75253,77237,77323,77527,77557,333323,352333,355723,375223,

%U 375233,375553,722333,727327,733333,735733,737353,737753,737773,753373,753527,772273,773273,775757,777353,777373

%N Larger of emirps (pairs) with only prime digits (A128388).

%H Harvey P. Dale, <a href="/A133753/b133753.txt">Table of n, a(n) for n = 1..1000</a>

%F {p in A128388: p> A004086(p)}. - _R. J. Mathar_, Jan 30 2008

%p read(transforms) : isA006567 := proc(n) local digs,prev ; if isprime(n) then prev := digrev(n) ; if n <> prev and isprime(prev) then true ; else false ; fi ; else false ; fi ; end: isA128388 := proc(n) local digs ; if isA006567(n) then digs := convert(convert(n,base,10),set) ; if digs minus {2,3,5,7} = {} then true ; else false ; fi ; else false ; fi ; end: isA133753 := proc(n) if isA128388(n) then if digrev(n) < n then true; else false ; fi ; else false ; fi ; end: for n from 1 to 200000 do p := ithprime(n) ; if isA133753(p) then printf("%d, ",p) ; fi ; od: # _R. J. Mathar_, Jan 30 2008

%t Select[(Table[(Sort/@Select[{#,IntegerReverse[#]}&/@Select[FromDigits/@Tuples[ {2,3,5,7},n],PrimeQ],AllTrue[#,PrimeQ]&])[[;;,2]]//Union,{n,2,6}]//Flatten//Union),!PalindromeQ[#]&] (* _Harvey P. Dale_, Sep 15 2024 *)

%Y Cf. A128388, A133554.

%K nonn,base

%O 1,1

%A _Lekraj Beedassy_, Jan 21 2008

%E Extended by _Ray Chandler_ and _R. J. Mathar_, Jan 30 2008