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 A120358 Even refactorable numbers n such that the number r of odd divisors and the number s of even divisors are both odd divisors of n and n is the first number for which the triple (r,s,t) occurs, where t is the number of divisors of n. 1

%I #3 Mar 30 2012 18:36:04

%S 2,18,72,450,1250,4050,16200,52488,56448,64800,71442,101250,198450,

%T 235298,285768,328050,405000,793800,1036800,1312200,1620000,1786050,

%U 3175200,4572288,4961250,5248800

%N Even refactorable numbers n such that the number r of odd divisors and the number s of even divisors are both odd divisors of n and n is the first number for which the triple (r,s,t) occurs, where t is the number of divisors of n.

%C Note that s is necessarily a multiple of r.

%e a(2)=18 since r=3, s=3 and r+s=6.

%Y Cf. A033950, A049439. A057265.

%K nonn

%O 1,1

%A _Walter Kehowski_, Jun 25 2006

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Last modified December 5 04:23 EST 2023. Contains 367569 sequences. (Running on oeis4.)