A073174 - OEIS

%I #11 May 30 2018 07:29:44

%S 0,1,1,2,2,2,3,3,4,5,5,5,7,7,9,10,7,8,11,10,14,15,11,12,16,15,18,21,

%T 18,18,25,22,29,32,21,21,23,23,30,34,27,23,34,34,41,48,30,27,41,37,41,

%U 48,43,45,59,54,38,43,39,41,57,46,64,82,48,52,70,55,84,99,70,57,86,86,102

%N a(n) = a(phi(n-1)) + a(phi(n-2)), a(0)=0, a(1)=1.

%H G. C. Greubel, <a href="/A073174/b073174.txt">Table of n, a(n) for n = 0..2000</a>

%t a[0]:= 0; a[1]:= 1; a[n_]:= a[EulerPhi[n - 1]] + a[EulerPhi[n - 2]];

%t Table[a[n], {n, 0, 50}] (* _G. C. Greubel_, May 29 2018 *)

%Y Cf. A000010.

%K easy,nonn

%O 0,4

%A _Labos Elemer_, Jul 22 2002