OFFSET
1,2
EXAMPLE
a(2)=2 because 12 and 21 (written in base 5) are primes (7 and 11).
MAPLE
A065846 := proc(n)
local b, u, udgs, uperm, a;
b :=5 ;
a := 0 ;
for u from b^(n-1) to b^n-1 do
udgs := convert(u, base, b) ;
prs := {} ;
for uperm in combinat[permute](udgs) do
if op(-1, uperm) <> 0 then
p := add( op(i, uperm)*b^(i-1), i=1..nops(uperm)) ;
if isprime(p) then
prs := prs union {p} ;
end if;
end if;
end do:
a := max(a, nops(prs)) ;
end do:
a ;
end proc:
for n from 1 do
print(n, A065846(n)) ;
end do: # R. J. Mathar, Apr 23 2016
MATHEMATICA
c[x_] := Module[{},
Length[Select[Permutations[x],
First[#] != 0 && PrimeQ[FromDigits[#, 5]] &]]];
A065846[n_] := Module[{i},
Return[Max[Map[c, DeleteDuplicatesBy[Tuples[Range[0, 4], n],
Table[Count[#, i], {i, 0, 4}] &]]]]];
Table[A065846[n], {n, 1, 9}] (* Robert Price, Mar 30 2019 *)
CROSSREFS
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
a(16) from Michael S. Branicky, May 29 2024
a(17) from Michael S. Branicky, Jun 26 2024
a(18) from Michael S. Branicky, Jul 08 2024
STATUS
approved