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 A068512 #3 Mar 30 2012 18:50:20 %S A068512 -1,0,-1,1,-3,1,-5,4,3,1,-9,5,-11,1,1,12,-15,6,-17,7,-1,1,-21,16,-5,1, %T A068512 27,9,-27,8,-29,32,-5,1,-11,21,-35,1,-7,24,-39,10,-41,13,33,1,-45,44, %U A068512 -21,10,-11,15,-51,27,-23,32,-13,1,-57,31,-59 %N A068512 Numerators of arithmetic derivative of n/2: A003415(n)/2 - n/4; denominators: A010685. %C A068512 For all k>0: a(2*k)=A003415(k) with denominator=A010685(2*k)=1; %C A068512 for primes p>2: a(2*p)=1 with denominator=A010685(2*p)=1, %C A068512 and a(p)=2-p with denominator=A010685(p)=4. %Y A068512 For definition of arithmetic derivative: A003415. %K A068512 sign %O A068512 1,5 %A A068512 _Reinhard Zumkeller_, Mar 19 2002