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%I #9 Nov 12 2019 23:45:01
%S 61,71,163,173,601,619,643,701,719,743,1609,1621,1709,1721,1861,1871,
%T 2689,2789,3361,3371,3671,3761,4261,4271,4363,4373,4603,4621,4651,
%U 4703,4721,4751,4861,4871,5563,5573,5641,5669,5683,5741,5779,5783,5869,5879
%N Primes that become a different prime under the mapping 6 <=> 7.
%H Robert Israel, <a href="/A180555/b180555.txt">Table of n, a(n) for n = 1..10000</a>
%H <a href="/index/Pri#primes">Index to Primes</a>, Primes that become a different prime under some mapping.
%p g:= proc(n) local L,i;
%p L:= subs({6=7,7=6},convert(n,base,10));
%p add(L[i]*10^(i-1),i=1..nops(L))
%p end proc:
%p filter:= proc(x) local y;
%p if not isprime(x) then return false fi;
%p y:= g(x);
%p y <> x and isprime(y)
%p end proc:
%p select(filter, [seq(i,i=3..10000,2)]); # _Robert Israel_, Nov 12 2019
%t fQ[n_] := Block[{id = IntegerDigits@n}, (MemberQ[id, 6] || MemberQ[id, 7]) && PrimeQ[ FromDigits[ id /. {6 -> 7, 7 -> 6}] ]]; Select[ Prime@ Range@ 780, fQ]
%Y Cf. A171040, A175791, A180517 thru A180559, A175789, A180560, A180561.
%K base,nonn
%O 1,1
%A _Zak Seidov_ and _Robert G. Wilson v_, Sep 09 2010
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