(* decimal integer to b-based digits 10進法ｘをｂ進法表記の文字リストに返還*)
i2d[x_,b_:16] :=(
digits=Flatten@{"0","1","2","3","4","5","6","7","8","9",Alphabet[]};
r=List@Mod[x,b];
q=Floor[x/b];
While[q > 0,PrependTo[r,Mod[q,b]];q=Floor[q/b]];
digits[[r+1]]
)

(* b-based digits to decimal integer ｂ進法表記文字列xを10進法の数に返還 *)
d2i[x_,b_:16] :=(
tonum[char_]:=(
digits=Flatten@{"0","1","2","3","4","5","6","7","8","9",Alphabet[]};
Position[digits,char][[1]][[1]]-1
);
ss=StringSplit[x,""];
d10=tonum /@ ss;
le=Length@ss;
Table[(Reverse@d10)[[i]]*b^(i-1),{i,1,le}]//Total
)
(* ハーシャッド数（ハーシャッドすう、英: harshad number）とは、自然数の各位の数字和が元の数の約数に含まれている自然数である。*)
harshadQ[n_,b_] := Divisible[n,Total[d2i[#,b]&/@i2d[n,b]]]
solve[start_:"1",end_:"ff",b_] :=(
li=Select[Range[d2i[start,b],d2i[end,b]],harshadQ[#,b]&];
re=i2d[#,b]& /@ li;
StringJoin /@ re
)