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a(0)=0, a(1)=1; at n>1 a(n) = a(n-1) + (sum of numbers<n among a(0),a(1),..,a(n-1) which are coprime to n).
1

%I #2 Mar 30 2012 17:26:22

%S 0,1,2,5,6,9,15,29,35,43,53,76,82,105,120,123,153,191,197,235,245,253,

%T 283,321,327,345,375,383,413,451,481,548,607,644,703,750,820,922,1016,

%U 1088,1127,1229,1264,1366,1503,1578,1715,1860,1973,2083,2165,2280,2417

%N a(0)=0, a(1)=1; at n>1 a(n) = a(n-1) + (sum of numbers<n among a(0),a(1),..,a(n-1) which are coprime to n).

%t s={0,1};b=1;Do[b=b+Total[Select[Range[n-1],GCD[ #1,n]==1&&MemberQ[s,#1]&]];AppendTo[s,b],{n,2,100}];s

%Y Cf. A122847.

%K nonn

%O 0,3

%A _Zak Seidov_, Oct 27 2006