A065848 Let u be any string of n digits from {0,...,6}; 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).

1, 2, 5, 15, 45, 154, 674, 3575, 14946, 68308, 345653, 1931846

Offset

1,2

Links

Table of n, a(n) for n=1..12.

Example

a(2)=2 because 14 and 41 (written in base 7) are primes (11 and 29).
a(3)=5 because 124, 142, 214, 241 and 421 (in base 7) are primes (67, 79, 109, 127 and 211). R. J. Mathar, Apr 23 2016

Mathematica

c[x_] := Module[{},
   Length[Select[Permutations[x],
     First[#] != 0 && PrimeQ[FromDigits[#, 7]] &]]];
A065848[n_] := Module[{i},
   Return[Max[Map[c, DeleteDuplicatesBy[Tuples[Range[0, 6], n],
       Table[Count[#, i], {i, 0, 6}] &]]]]];
Table[A065848[n], {n, 1, 7}] (* Robert Price, Mar 30 2019 *)

Crossrefs

Cf. A065843, A065844, A065845, A065846, A065847, A065849, A065850, A065851, A065852, A065853

Sequence in context: A149912 A148358 A149913 * A148359 A287582 A122392

Adjacent sequences: A065845 A065846 A065847 * A065849 A065850 A065851

Keyword

base,more,nonn

Author

Sascha Kurz, Nov 24 2001

Extensions

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

Definition corrected by David A. Corneth, Apr 23 2016

Status

approved