A065850 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).

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

Offset: 1

Author

Sascha Kurz, Nov 24 2001

Keywords

• base
• more
• nonn

Examples

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

Crossrefs

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

Programs

Mathematica

c[x_] := Module[{},
   Length[Select[Permutations[x],
     First[#] != 0 && PrimeQ[FromDigits[#, 9]] &]]];
A065850[n_] := Module[{i},
   Return[Max[Map[c, DeleteDuplicatesBy[Tuples[Range[0, 8], n],
       Table[Count[#, i], {i, 0, 8}] &]]]]];
Table[A065850[n], {n, 1, 7}] (* Robert Price, Mar 30 2019 *)

Extensions

a(10)-a(11) from Sean A. Irvine, Sep 06 2009

Definition corrected by David A. Corneth, Apr 23 2016

a(12) from Michael S. Branicky, Jul 03 2024

a(13) from Michael S. Branicky, Jul 09 2024