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a[n] is the smallest integer with property that phi[n+a[n]]=sigma[n].
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%I #4 Oct 15 2013 22:32:23

%S 1,3,5,3,19,3,7,3,11,23,5,19,6,23,7,47,6,14,6,7,15,11,43,46,10,20,6,

%T 11,33,23,45,22,6,15,14,38,51,15,14,21,10,41,12,19,27,23,69,22,24,22,

%U 15,14,15,14,21,26,23,55,15,14,30,20,23,87,15,14,31,26,27,139,15,14,35,20,33

%N a[n] is the smallest integer with property that phi[n+a[n]]=sigma[n].

%F Least solution to Min{x; phi[x+n]=sigma[x]}.

%e n=6:a[6]=19 because sigma[19]=20=phi[19+6]=phi[25]=20.

%e n=16:a[16]=23 because sigma[23]=24=phi[23+16]=phi[39]=24

%Y Cf. A007015, A007365.

%K nonn

%O 1,2

%A _Labos Elemer_, May 11 2004