cp's OEIS Frontend

A065849 Let u be any string of n digits from {0,...,7}; let f(u) = number of distinct primes, not beginning with 0, formed by permuting the digits of u to a base-8 number; then a(n) = max_u f(u).

%I A065849 #29 Jul 22 2024 15:22:10
%S A065849 1,2,3,11,23,113,425,1912,11872,57918,303157,1757094,9777949,59129172
%N A065849 Let u be any string of n digits from {0,...,7}; let f(u) = number of distinct primes, not beginning with 0, formed by permuting the digits of u to a base-8 number; then a(n) = max_u f(u).
%e A065849 a(2)=2 because 15 and 51 (written in base 8) are primes (13 and 41).
%e A065849 a(3)=3 because 531, 351 and 513 (in base 8) are primes (107, 233, 331), or 145, 415 and 541 (in base 8) are primes (101, 269, 353), or 147, 417 and 471 are primes (103, 271, 313) etc. - _R. J. Mathar_, Apr 23 2016
%t A065849 c[x_] := Module[{},
%t A065849    Length[Select[Permutations[x],
%t A065849      First[#] != 0 && PrimeQ[FromDigits[#, 8]] &]]];
%t A065849 A065849[n_] := Module[{i},
%t A065849    Return[Max[Map[c, DeleteDuplicatesBy[Tuples[Range[0, 7], n],
%t A065849        Table[Count[#, i], {i, 0, 7}] &]]]]];
%t A065849 Table[A065849[n], {n, 1, 7}] (* _Robert Price_, Mar 30 2019 *)
%Y A065849 Cf. A065843, A065844, A065845, A065846, A065847, A065848, A065850, A065851, A065852, A065853.
%K A065849 base,more,nonn
%O A065849 1,2
%A A065849 _Sascha Kurz_, Nov 24 2001
%E A065849 2 more terms from _Sean A. Irvine_, Sep 06 2009
%E A065849 Definition corrected by _David A. Corneth_, Apr 23 2016
%E A065849 a(13) from _Michael S. Branicky_, Jul 08 2024
%E A065849 a(14) from _Michael S. Branicky_, Jul 22 2024