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 A180581 Least prime p which maps into n different primes under some mapping of a single decimal digit <=> with another single decimal digit. 0
 11, 1187, 449, 2, 61, 29, 19, 23, 17, 13, 109, 1021, 107, 10427, 78041, 10457, 190583, 1309757, 2531689, 152944307 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS a(n) > 10^9 for n >= 20. [From Donovan Johnson, Oct 05 2010] LINKS Index to Primes, Primes that become a different prime under some mapping. MATHEMATICA 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 CROSSREFS Cf. A171057, A175791, A180517 thru A180559, A175789, A180560, A180561. Sequence in context: A177068 A222827 A067105 * A019524 A078269 A015009 Adjacent sequences:  A180578 A180579 A180580 * A180582 A180583 A180584 KEYWORD base,fini,nonn AUTHOR Robert G. Wilson v, Sep 10 2010 EXTENSIONS a(19) from Donovan Johnson, Oct 05 2010 STATUS approved

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