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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).
11
1, 2, 5, 11, 39, 161, 865, 4604, 22636, 161107, 840691, 4813328, 29664164
OFFSET
1,2
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 *)
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