Search: id:A061795
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%I A061795
%S A061795 1,1,3,3,6,6,9,9,9,9,13,13,17,17,18,18,22,22,26,26,26,26,30,30,32,32,
%T A061795 32,32,37,37,41,41,41,41,43,43,47,47,47,47,53,53,57,57,57,57,62,62,62,
%U A061795 62,63,63,67,67,67,67,67,67,72,72,79,79,79,79,81,81,86,86,87,87,93,93
%N A061795 Number of distinct sums phi(i) + phi(j) for 1<=i<=j<=n, phi(k) = A000010(k).
%e A061795 If the {s+t} sums are generated by adding 2 terms of an S set consisting 
               of n different entries, then at least 1, at most n(n+1)/2=A000217(n) 
               distinct values can be obtained. The set of first n Phi-values gives 
               results falling between these two extremes. E.g. n=10, A000010:{1,
               1,2,2,4,2,6,4,6,4...}. Additions provide {2,3,4,5,6,7,8,10,12}, i.e. 
               9 different results. Thus a(10)=9.
%t A061795 f[x_] := EulerPhi[x] t0=Table[Length[Union[Flatten[Table[f[u]+f[w], {w, 
               1, m}, {u, 1, m}]]]], {m, 1, 75}]
%Y A061795 A000217, A000010.
%Y A061795 Sequence in context: A070318 A023842 A165885 this_sequence A110261 A049318 
               A079551
%Y A061795 Adjacent sequences: A061792 A061793 A061794 this_sequence A061796 A061797 
               A061798
%K A061795 nonn
%O A061795 1,3
%A A061795 Labos E. (labos(AT)ana.sote.hu), Jun 22 2001

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