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A065853 Let u be any string of 4 digits from {0,...,n-1}; let f(u) = number of distinct primes, not beginning with 0, formed by permuting the digits of u; then a(n) = max_u f(u). 11

%I

%S 2,4,6,7,8,15,11,11,11,15,15,19,11,14,15,14,11,16,13,18,14,14,14,16,

%T 13,16,15,17,13,16,14,15,17,16,15,16,14,17,14,17,16,17,14,16,15,15,14,

%U 17,17,16,16,16,15,18,16,17,14,15,14,16,15,15,16,16,17,17,13,17,15,17,13

%N Let u be any string of 4 digits from {0,...,n-1}; let f(u) = number of distinct primes, not beginning with 0, formed by permuting the digits of u; then a(n) = max_u f(u).

%e a(2)=2 because 1101 and 1011 are primes and there are no three 4-digit primes with the same number of ones in base 2.

%t c[x_, n_] :=

%t Module[{},

%t Length[Select[Permutations[x],

%t First[#] != 0 && PrimeQ[FromDigits[#, n]] &]]];

%t A065853[n_] := Module[{i},

%t Return[ Max[Map[c[#, n] &,

%t DeleteDuplicatesBy[Tuples[Range[0, n - 1], 4],

%t Table[Count[#, i], {i, 0, n - 1}] &]]]]];

%t Table[A065853[n], {n, 2, 20}] (* _Robert Price_, Mar 30 2019 *)

%Y Cf. A065843, A065844, A065845, A065846, A065847, A065848, A065849, A065850, A065851, A065852

%K base,nonn

%O 2,1

%A _Sascha Kurz_, Nov 24 2001

%E Definition corrected by _David A. Corneth_, Apr 23 2016

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Last modified January 24 01:05 EST 2020. Contains 331178 sequences. (Running on oeis4.)