A098426 - OEIS

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A098426

a(n)=(1/2)*sum(i=0,n,rad(binomial(n,i))) where rad(k)=A007947(k).

%I #5 Mar 30 2012 18:39:23

%S 1,2,4,6,16,27,64,66,94,287,1024,645,2380,6723,12094,7136,36772,38733,

%T 161254,241083,571714,1203173,4194304,2005009,2162496,8739877,6699838,

%U 27330423,112844656,41322885,252807388,201501336,419398108,2840231975

%N a(n)=(1/2)*sum(i=0,n,rad(binomial(n,i))) where rad(k)=A007947(k).

%C For n>1 a(n) odd seems to imply 2*phi(n)<n where phi= totient function.

%K nonn

%O 1,2

%A _Benoit Cloitre_, Oct 26 2004