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

1,2

Links

Table of n, a(n) for n=1..13.

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

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

Status

approved