%I #4 Mar 30 2012 18:50:31
%S 0,0,1,2,3,1,0,5,4,3,3,7,2,4,4,10,3,6,5,12,4,3,6,16,9,6,7,13,10,10,7,
%T 16,6,9,8,25,9,9,10,22,13,13,12,19,10,9,16,29,10,16,14,24,10,21,17,31,
%U 9,13,20,37,16,14,18,30,18,20,21,35,13,16,27,49,21,15,13,42,22,25,19,39,26
%N Number of numbers k<=n with mu(k+n)=mu(k), where mu=A008683 (Moebius function).
%e n=10: mu(3+10)=mu(3)=-1, mu(7+10)=mu(7)=-1, mu(8+10)=mu(8)=0 and mu(k+10)<>mu(k) for k in {1,2,4,5,6,8,9}, therefore a(10)=3.
%Y Cf. A081248.
%K nonn
%O 1,4
%A _Reinhard Zumkeller_, Mar 12 2003