A065849 Let u be any string of n digits from {0,...,7}; let f(u) = number of distinct primes, not beginning with 0, formed by permuting the digits of u to a base-8 number; then a(n) = max_u f(u).

1, 2, 3, 11, 23, 113, 425, 1912, 11872, 57918, 303157, 1757094, 9777949, 59129172

Offset: 1

Author

Sascha Kurz, Nov 24 2001

Keywords

• base
• more
• nonn

Examples

			a(2)=2 because 15 and 51 (written in base 8) are primes (13 and 41).
a(3)=3 because 531, 351 and 513 (in base 8) are primes (107, 233, 331), or 145, 415 and 541 (in base 8) are primes (101, 269, 353), or 147, 417 and 471 are primes (103, 271, 313) etc. - _R. J. Mathar_, Apr 23 2016
		

Crossrefs

Cf. A065843, A065844, A065845, A065846, A065847, A065848, A065850, A065851, A065852, A065853.

Programs

Mathematica

c[x_] := Module[{},
   Length[Select[Permutations[x],
     First[#] != 0 && PrimeQ[FromDigits[#, 8]] &]]];
A065849[n_] := Module[{i},
   Return[Max[Map[c, DeleteDuplicatesBy[Tuples[Range[0, 7], n],
       Table[Count[#, i], {i, 0, 7}] &]]]]];
Table[A065849[n], {n, 1, 7}] (* Robert Price, Mar 30 2019 *)

Extensions

2 more terms from Sean A. Irvine, Sep 06 2009

Definition corrected by David A. Corneth, Apr 23 2016

a(13) from Michael S. Branicky, Jul 08 2024

a(14) from Michael S. Branicky, Jul 22 2024