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Least prime p which maps into n different primes under some mapping of a single decimal digit <=> with another single decimal digit.
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%I #6 Mar 30 2012 17:35:02

%S 11,1187,449,2,61,29,19,23,17,13,109,1021,107,10427,78041,10457,

%T 190583,1309757,2531689,152944307

%N Least prime p which maps into n different primes under some mapping of a single decimal digit <=> with another single decimal digit.

%C a(n) > 10^9 for n >= 20. [From _Donovan Johnson_, Oct 05 2010]

%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, s[[1]]] || MemberQ[id, s[[2]]]) && PrimeQ[FromDigits[id /. {s[[1]] -> s[[2]], s[[2]] -> s[[1]]}]]]; f[n_] := Count[ Flatten[ Table[s = {j, k}; fQ@n, {j, 0, 8}, {k, j + 1, 9}]], True]; t = Table[0, {46}]; p = 2; While[p < 13500000, a = f@p; If[ t[[a + 1]] == 0, t[[a + 1]] = p; Print[{a, p}]]; p = NextPrime@p]; t

%Y Cf. A171057, A175791, A180517 thru A180559, A175789, A180560, A180561.

%K base,fini,nonn

%O 0,1

%A _Robert G. Wilson v_, Sep 10 2010

%E a(19) from _Donovan Johnson_, Oct 05 2010