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 A084688 #37 Aug 05 2015 04:07:44
%S A084688 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,20,29
%N A084688 Nonnegative integers n such that 2^n uses only distinct decimal digits.
%C A084688 There are exactly 18 numbers such that 2^n uses only distinct digits.
%C A084688 a(n) can have at most 10 digits. As 2^34 has 11 digits, a(n) < 34. - _David A. Corneth_, Aug 03 2015
%C A084688 Subsequence of A052060. - _R. J. Mathar_, Sep 17 2008
%F A084688 a(n) = log_2(A260814(n)). - _Zak Seidov_, Aug 02 2015
%e A084688 29 is the last term with 2^29 = 536870912 = A260814(18). - _Zak Seidov_, Aug 02 2015
%t A084688 Select[Range[0, 34], Max@ DigitCount[2^#] == 1 &] (* _Michael De Vlieger_, Aug 03 2015 *) (* with corrections by _Zak Seidov_, Aug 05 2015 *)
%o A084688 (PARI) lista() = {lim = ceil(log(10^11)/(log(2)));for (n=0, lim, d = digits(2^n); if (#vecsort(d,,8) == #d, print1(n, ", ")););} \\ _Michel Marcus_, Aug 03 2015
%Y A084688 Cf. A000079, A260814, A052060.
%K A084688 fini,nonn,full,base
%O A084688 1,3
%A A084688 _Zak Seidov_, Jul 01 2003