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%I #17 Apr 18 2021 02:18:12
%S 4,8,9,15,20,21,25,33,39,44,48,49,50,55,69,70,72,76,85,91,92,108,110,
%T 111,112,115,116,129,130,133,135,141,154,159,162,168,169,170,182,183,
%U 201,213,230,235,236,242,244,253,259,265,266,284,286,288,295,297,309
%N Composite numbers k such that k - (number of prime factors of k, counted with multiplicity) is a prime.
%H Robert Israel, <a href="/A158337/b158337.txt">Table of n, a(n) for n = 1..10000</a>
%e 4 is a term: 4 = 2*2 has 2 prime factors (counted with multiplicity), and 4 - 2 = 2 (a prime).
%e 8 is a term: 8 = 2*2*2 has 3 prime factors, and 8 - 3 - 5 (a prime).
%e 9 is a term: 9 = 3*3 has 2 prime factors, and 9 - 2 = 7 (a prime).
%p select(t -> not isprime(t) and isprime(t - numtheory:-bigomega(t)), [$4..1000]); # _Robert Israel_, Apr 08 2018
%t Select[Range[350],CompositeQ[#]&&PrimeQ[#-PrimeOmega[#]]&] (* _Harvey P. Dale_, Apr 01 2019 *)
%Y Cf. A000040, A002808, A069345.
%K nonn
%O 1,1
%A _Juri-Stepan Gerasimov_, Mar 16 2009, Nov 14 2009
%E Entries checked by _R. J. Mathar_, May 19 2010
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