%I #12 Jun 25 2018 22:55:15
%S 1,2,3,8,10,24,42,128,162,400,682,1920,2730,6272,9900,32768,43690,
%T 93312,174762,493440,682668,1672704,2796202,8257536,10125000,26153088,
%U 42384060,126322560,175923744,380160000,715827882,2144133120
%N Half totient of 2^n+1.
%H Harry J. Smith, <a href="/A063474/b063474.txt">Table of n, a(n) for n = 1..250</a>
%F a(n) = A023022(A000051(n)).
%o (PARI) H(n)=eulerphi(n)/2; j=[]; for(n=1,40,j=concat(j,H(2^n+1))); j
%o (PARI) { for (n=1, 250, write("b063474.txt", n, " ", eulerphi(2^n + 1)/2) ) } \\ _Harry J. Smith_, Aug 22 2009
%Y Cf. A023022, A000051.
%K nonn
%O 1,2
%A _Jason Earls_, Jul 27 2001