%I #3 Mar 30 2012 16:50:05
%S 2,4,8,20,60,188,632,2192,7712,27596,99880,364724,1342184,4971068,
%T 18512792,69273668,260301176,981706832,3714566312,14096303344,
%U 53634713552,204560302844,781874936816,2994414645860,11488774559636
%N Bisection of A000031.
%p with(numtheory):seq((1/(2*n+1))*add(phi(d)*2^((2*n+1)/d),d=divisors(2*n+1)),n=0..30); (C. Ronaldo)
%Y Cf. A000031, A100446. Equals 2*A026119.
%K nonn,easy
%O 0,1
%A _N. J. A. Sloane_, Nov 21 2004
%E More terms from C. Ronaldo (aga_new_ac(AT)hotmail.com), Jan 19 2005