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Primes that become a different prime under the mapping 2 <=> 9.
1

%I #11 Oct 30 2023 11:14:20

%S 127,197,211,227,241,271,277,283,421,491,523,593,727,797,911,941,971,

%T 977,983,997,1021,1091,1123,1193,1201,1213,1223,1231,1423,1493,1627,

%U 1697,1901,1913,1931,1993,2011,2137,2161,2207,2267,2273,2293,2311,2341

%N Primes that become a different prime under the mapping 2 <=> 9.

%H Robert Price, <a href="/A180539/b180539.txt">Table of n, a(n) for n = 1..2084</a>

%H <a href="/index/Pri#primes">Index to Primes</a>, Primes that become a different prime under some mapping.

%t fQ[n_] := Block[{id = IntegerDigits@n}, (MemberQ[id, 2] || MemberQ[id, 9]) && PrimeQ[ FromDigits[ id /. {2 -> 9, 9 -> 2}] ]]; Select[ Prime@ Range@ 350, fQ]

%Y Cf. A171051, A175791, A180517 thru A180559, A175789, A180560, A180561.

%K base,nonn

%O 1,1

%A _Zak Seidov_ and _Robert G. Wilson v_, Sep 09 2010