a=21*5*21*5*21

bbb[1] = 1;
bbb[n_]:=bbb[n]=bbb[n-1](a-n+1)/a

ccc[n_, ac_]:=N[1-bbb[n], ac]

ttt[m_,n_, ac_]:=Table[{i, ccc[i, ac]}, {i, m,n}];

TableForm@ttt[560,570, 10]

Graphics[{Blue,Line[ttt[1,3000,30]], Red, Line[{{0,.5},{3000,.5}}], Line[{{567,0},{567,1}}]}, AspectRatio->.6, Axes->True]

CharacterRange["A","Z"][[

c[]:={"B","C","D","F","G","H","J","K","L","M","N","P","Q","R","S","T","V","W","X","Y","Z"}[[RandomInteger[{1, 21}]]];
v[]:={"A","E","I","O","U"}[[RandomInteger[{1, 5}]]]

cvcvc[]:=c[]<>v[]<>c[]<>v[]<>c[]

Reverse@Sort[Map[Reverse,Tally[Table[cvcvc[], {600}]]]]