%I A037063
%S A037063 5,557,5557,155557,555557,15555557,55555553,3555555551,5555555557,
%T A037063 525555555557,555555555551,5555555555551,355555555555559,
%U A037063 555555555555557,51555555555555551,545555555555555551
%N A037063 Smallest prime containing exactly n 5's.
%t A037063 f[n_, b_] := Block[{k = 10^(n + 1), p = Permutations[ Join[ Table[b, 
               {i, 1, n}], {x}]], c = Complement[Table[j, {j, 0, 9}], {b}], q = 
               {}}, Do[q = Append[q, Replace[p, x -> c[[i]], 2]], {i, 1, 9}]; r 
               = Min[ Select[ FromDigits /@ Flatten[q, 1], PrimeQ[ # ] & ]]; If[r 
               ? Infinity, r, p = Permutations[ Join[ Table[ b, {i, 1, n}], {x, 
               y}]]; q = {}; Do[q = Append[q, Replace[p, {x -> c[[i]], y -> c[[j]]}, 
               2]], {i, 1, 9}, {j, 1, 9}]; Min[ Select[ FromDigits /@ Flatten[q, 
               1], PrimeQ[ # ] & ]]]]; Table[ f[n, 5], {n, 1, 18}]
%Y A037063 Cf. A065588, A037062, A034388, A036507-A036536.
%Y A037063 Cf. A037053, A037055, A037057, A037059, A037061, A037065, A037067, A037069, 
               A037071.
%Y A037063 Sequence in context: A110721 A067446 A112900 this_sequence A153404 A093941 
               A072952
%Y A037063 Adjacent sequences: A037060 A037061 A037062 this_sequence A037064 A037065 
               A037066
%K A037063 nonn,base
%O A037063 1,1
%A A037063 Patrick De Geest (pdg(AT)worldofnumbers.com), Jan 04 1999.
%E A037063 More terms from Randall Rathbun, Jan 11 2002
%E A037063 Edited and corrected by Robert G. Wilson v (rgwv(AT)rgwv.com), Jul 04 
               2003