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A289182 Positions of odd semiprimes in A001358. 13

%I

%S 3,6,7,9,11,13,15,17,18,19,20,23,24,26,28,30,31,32,34,36,37,39,40,42,

%T 43,44,46,48,49,51,53,54,56,57,59,60,61,63,65,66,68,69,71,72,74,75,77,

%U 78,79,80,81,83,85,86,89,90,91,92,94,95,97,98

%N Positions of odd semiprimes in A001358.

%C Complement to A115392.

%F a(n) ~ n. - _Charles R Greathouse IV_, Jul 02 2017

%t sp=Select[Range[4,1000],2==PrimeOmega[#]&];Flatten[Position[Mod[sp, 2],1]]

%o (PARI) lista(nn) = vsp = select(x->(bigomega(x)==2), vector(nn, k, k)); select(x->(x%2), vsp, 1); \\ _Michel Marcus_, Jul 02 2017

%Y Cf. A001358, A115392.

%K nonn

%O 1,1

%A _Zak Seidov_, Jun 27 2017

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Last modified July 27 07:36 EDT 2021. Contains 346304 sequences. (Running on oeis4.)