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A045766 Number of prime factors of double factorials n!! (A006882), with multiplicity. 0

%I

%S 0,1,1,3,2,5,3,8,5,10,6,13,7,15,9,19,10,22,11,25,13,27,14,31,16,33,19,

%T 36,20,39,21,44,23,46,25,50,26,52,28,56,29,59,30,62,33,64,34,69,36,72,

%U 38,75,39,79,41,83,43,85,44,89,45,91,48,97,50,100,51,103,53,106,54,111

%N Number of prime factors of double factorials n!! (A006882), with multiplicity.

%H <a href="/index/Fa#factorial">Index entries for sequences related to factorial numbers</a>

%e 8!!=8*6*4*2=2^3*2*3*2^2*2=2^7*3. Eight prime factors, so a(8)=8.

%t PrimeOmega[Range[80]!!] (* _Harvey P. Dale_, May 29 2015 *)

%K nonn,easy

%O 1,4

%A _Jeff Burch_

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Last modified February 6 17:09 EST 2023. Contains 360110 sequences. (Running on oeis4.)