A065850 - OEIS

%I #31 Jul 09 2024 23:25:20

%S 1,2,5,11,39,161,865,4604,22636,161107,840691,4813328,29664164

%N Let u be any string of n digits from {0,...,8}; let f(u) = number of distinct primes, not beginning with 0, formed by permuting the digits of u to a base-9 number; then a(n) = max_u f(u).

%e a(2)=2 because 12 and 21 (written in base 9) are primes (11 and 19).

%t c[x_] := Module[{},

%t    Length[Select[Permutations[x],

%t      First[#] != 0 && PrimeQ[FromDigits[#, 9]] &]]];

%t A065850[n_] := Module[{i},

%t    Return[Max[Map[c, DeleteDuplicatesBy[Tuples[Range[0, 8], n],

%t        Table[Count[#, i], {i, 0, 8}] &]]]]];

%t Table[A065850[n], {n, 1, 7}] (* _Robert Price_, Mar 30 2019 *)

%Y Cf. A065843, A065844, A065845, A065846, A065847, A065848, A065849, A065851, A065852, A065853.

%K base,more,nonn

%O 1,2

%A _Sascha Kurz_, Nov 24 2001

%E a(10)-a(11) from _Sean A. Irvine_, Sep 06 2009

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

%E a(12) from _Michael S. Branicky_, Jul 03 2024

%E a(13) from _Michael S. Branicky_, Jul 09 2024