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 A272698 #15 Aug 20 2017 12:53:10
%S A272698 2,4,8,16,32,512
%N A272698 Powers of 2 with exactly one even decimal digit.
%C A272698 The number of even digits of powers of 2 is more than 0. However, it seems there are few powers of 2 with 1 even digit.
%C A272698 If there are any other terms in this sequence, they are greater than 2^10^10. - _Charles R Greathouse IV_, May 04 2016
%t A272698 Select[2^Range[0, 50000], Total@ Pick[DigitCount@ #, {0, 1, 0, 1, 0, 1, 0, 1, 0, 1}, 1] == 1 &] (* _Michael De Vlieger_, May 04 2016 *)
%t A272698 Select[2^Range[200],Count[IntegerDigits[#],_?EvenQ]==1&] (* _Harvey P. Dale_, Aug 20 2017 *)
%o A272698 (Ruby)
%o A272698 ary = []
%o A272698 s = 1
%o A272698 (1..10 ** 4).each{|i|
%o A272698 s *= 2
%o A272698 j = s.to_s.split('').map(&:to_i).select{|i| i % 2 == 0}.size
%o A272698 ary << s if j == 1
%o A272698 }
%o A272698 p ary
%o A272698 (PARI) is(n)=my(d=digits(n)); n>1 && n>>valuation(n,2)==1 && sum(i=1,#d,d[i]%2==0)==1 \\ _Charles R Greathouse IV_, May 04 2016
%K A272698 nonn,base
%O A272698 1,1
%A A272698 _Seiichi Manyama_, May 04 2016