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 A071650 #12 Jul 27 2020 14:55:19
%S A071650 1,-2,3,-4,5,-6,7,-8,9,1,2,-1,4,-3,6,-5,8,-7,10,-2,-1,-4,1,-6,3,-8,5,
%T A071650 -10,7,3,4,1,6,-1,8,-3,10,-5,12,-4,-3,-6,-1,-8,1,-10,3,-12,5,5,6,3,8,
%U A071650 1,10,-1,12,-3,14,-6,-5,-8,-3,-10,-1,-12,1,-14,3,7,8,5,10
%N A071650 Difference between sums of odd and even digits of n.
%H A071650 Michel Marcus, <a href="/A071650/b071650.txt">Table of n, a(n) for n = 1..10000</a>
%F A071650 a(n) = A071649(n) - A071648(n);
%F A071650 a(A036301(n)) = 0.
%t A071650 Table[Total[Select[IntegerDigits[n],OddQ]]-Total[Select[ IntegerDigits[ n],EvenQ]],{n,80}] (* _Harvey P. Dale_, Jul 27 2020 *)
%o A071650 (PARI) a(n) = {my(d=digits(n), s = 0); for (k=1, #d, if (d[k] % 2, s += d[k], s -= d[k]);); s;} \\ _Michel Marcus_, Aug 05 2017
%o A071650 (PARI) A071650(n)=-vecsum(apply(t->(-1)^t*t,digits(n))) \\ _M. F. Hasler_, Dec 09 2018
%Y A071650 Cf. A036301, A071648, A071649.
%K A071650 sign,look,base
%O A071650 1,2
%A A071650 _Reinhard Zumkeller_, May 28 2002