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; then a(n) = max_u f(u).

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

Offset

1,2

Links

Table of n, a(n) for n=1..11.

Example

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

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 *)

Crossrefs

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

Sequence in context: A001344 A056302 A276547 * A191029 A106886 A237814

Adjacent sequences: A065847 A065848 A065849 * A065851 A065852 A065853

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