%I A081247
%S A081247 0,0,1,2,3,1,0,5,4,3,3,7,2,4,4,10,3,6,5,12,4,3,6,16,9,6,7,13,10,10,7,16,
%T A081247 6,9,8,25,9,9,10,22,13,13,12,19,10,9,16,29,10,16,14,24,10,21,17,31,9,13,
%U A081247 20,37,16,14,18,30,18,20,21,35,13,16,27,49,21,15,13,42,22,25,19,39,26
%N A081247 Number of numbers k<=n with mu(k+n)=mu(k), where mu=A008683 (Moebius 
               function).
%e A081247 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 A081247 Cf. A081248.
%Y A081247 Sequence in context: A115352 A038554 A100329 this_sequence A144633 A005210 
               A048994
%Y A081247 Adjacent sequences: A081244 A081245 A081246 this_sequence A081248 A081249 
               A081250
%K A081247 nonn
%O A081247 1,4
%A A081247 Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Mar 12 2003