A064085 - OEIS

%I #10 Jan 13 2025 04:06:45

%S 1,1,1,1,1,3,1,1,1,11,1,39,1,43,151,1,1,171,1,2255,2359,683,1,9399,1,

%T 2731,1,140911,1,1649373,1,1,599479,43691,8727391,8965359,1,174763,

%U 9588151,139090655,1,1649061309,1,572942063,2221095391,2796203,1

%N Quotient of A000225 and A064084.

%C a(n) is equal to 1 if and only if n is a prime power; the sequence of nontrivial values of a is A064086.

%H Alois P. Heinz, <a href="/A064085/b064085.txt">Table of n, a(n) for n = 1..1000</a>

%F a(n) = A000225(n) / A064084(n).

%p a:= n-> (2^n-1)/mul(2^(i[1]^i[2])-1, i=ifactors(n)[2]):

%p seq(a(n), n=1..50);  # _Alois P. Heinz_, Jun 09 2014

%t a[n_] := (2^n-1)/Times @@ (2^(Power @@@ FactorInteger[n])-1);

%t Table[a[n], {n, 1, 50}] (* _Jean-François Alcover_, Jan 13 2025 *)

%Y Cf. A000225, A064084, A064086.

%K easy,nonn

%O 1,6

%A _Jens Voß_, Sep 04 2001

%E More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Mar 29 2003