login
a(n) = A000010(A064216(n)).
9

%I #18 Dec 21 2023 10:23:09

%S 1,1,2,4,2,6,10,2,12,16,4,18,6,4,22,28,6,8,30,10,36,40,4,42,20,12,46,

%T 12,16,52,58,8,20,60,18,66,70,6,24,72,8,78,24,22,82,40,28,32,88,12,96,

%U 100,8,102,106,30,108,36,20,48,42,36,18,112,40,126,64,8,130,136,42,60,44,20,138,148,24,56,150,46,72,156,12,162,110,32,166,24,52,172,178

%N a(n) = A000010(A064216(n)).

%H Antti Karttunen, <a href="/A285702/b285702.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = A000010(A064216(n)).

%F Sum_{k=1..n} a(k) ~ c * n^2, where c = Product_{p prime} (p^3/((p+1)*(p^2-q(p)))) = 0.5366875995..., where q(p) = prevprime(p) (A151799) if p > 2 and q(2) = 1. - _Amiram Eldar_, Dec 21 2023

%t Table[EulerPhi@ If[n == 1, 1, Apply[Times, FactorInteger[2 n - 1] /. {p_, e_} /; p > 2 :> NextPrime[p, -1]^e]], {n, 91}] (* _Michael De Vlieger_, Apr 26 2017 *)

%o (Scheme) (define (A285702 n) (A000010 (A064216 n)))

%Y Cf. A000010, A064216, A064989, A099774, A151799, A285703.

%Y Odd bisection of the following sequences: A347115, A348045, A349127, A349128.

%K nonn

%O 1,3

%A _Antti Karttunen_, Apr 26 2017