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 A065844 Let u be any string of n digits from {0,1,2}; 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). 11
 1, 2, 2, 4, 7, 19, 42, 102, 252, 532, 1226, 3681, 9100, 24858, 61943, 161857, 392935, 1167208, 3125539, 8879693, 23143081, 63028550 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS EXAMPLE a(2)=2 because 12 and 21 (written in base 3) are primes (5 and 7). MAPLE A065844 := proc(n)     local b, u, udgs, uperm, a;     b :=3 ;     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, A065844(n)) ; end do: # R. J. Mathar, Apr 23 2016 MATHEMATICA c[x_] := Module[{},    Length[Select[Permutations[x],      First[#] != 0 && PrimeQ[FromDigits[#, 3]] &]]]; A065844[n_] := Module[{i},    Return[Max[Map[c, DeleteDuplicatesBy[Tuples[Range[0, 2], n],        Table[Count[#, i], {i, 0, 2}] &]]]]]; Table[A065844[n], {n, 1, 13}] (* Robert Price, Mar 30 2019 *) CROSSREFS Cf. A065843, A065845, A065846, A065847, A065848, A065849, A065850, A065851, A065852, A065853 Sequence in context: A032441 A238184 A340333 * A131199 A112059 A093094 Adjacent sequences:  A065841 A065842 A065843 * A065845 A065846 A065847 KEYWORD base,nonn,more AUTHOR Sascha Kurz, Nov 24 2001 EXTENSIONS 3 more terms from Sean A. Irvine, Sep 06 2009 Definition corrected by David A. Corneth, Apr 23 2016 STATUS approved

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Last modified July 27 07:36 EDT 2021. Contains 346304 sequences. (Running on oeis4.)