A180581 Least prime p which maps into n different primes under some mapping of a single decimal digit <=> with another single decimal digit.

11, 1187, 449, 2, 61, 29, 19, 23, 17, 13, 109, 1021, 107, 10427, 78041, 10457, 190583, 1309757, 2531689, 152944307

Offset

0,1

Comments

a(n) > 10^9 for n >= 20. [From Donovan Johnson, Oct 05 2010]

Links

Table of n, a(n) for n=0..19.

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: A222827 A067105 A237695 * A233012 A019524 A274766

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