This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A126688 #10 Dec 26 2024 19:52:13
%S A126688 2,2,3,4,3,3,3,4,4,5,3,4,4,4,3,5,5,4,3,5,3,5,5,4,6,6,4,4,5,4,6,6,4,6,
%T A126688 4,4,7,5,4,5,6,5,7,4,4,7,5,5,4,4,5,4,5,4,5,4,4,5,5,6,8,6,6,9,5,5,7,6,
%U A126688 5,5,5,7,5,7,4,5,5,4,5,5,6,5,6,5,5,5,7,7,5,6,6,8,7,6,5,5,5,8,4,11
%N A126688 Lowest base in which n has distinct digits.
%C A126688 Start with binary and work upwards, expressing n in the given base (2,3,4... b). The term a(n)=b is the lowest base in which no two digits in n are the same.
%C A126688 See A123699 for another version of the same sequence. - _R. J. Mathar_, Jun 15 2008
%e A126688 75 is 1001011 in binary (base 2), 2210 in base 3 and 1023 in base 4. So a(75) = 4 since 1023 has distinct digits (and neither 1001011 nor 2210 do).
%t A126688 Table[ b=1;Until[Length[Union[IntegerDigits[n,b]]]==Length[IntegerDigits[n,b]],b++];b,{n,100}] (* _James C. McMahon_, Dec 26 2024 *)
%Y A126688 Cf. A010784 (base 10), A062813 (gives lower bound for a term).
%K A126688 nonn,base
%O A126688 1,1
%A A126688 _Paul Richards_, Feb 15 2007