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Odd n > 1 such that n+1 is a semiprime times a power of two.
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%I #10 Oct 22 2024 03:27:27

%S 7,11,15,17,19,23,27,29,31,35,39,41,43,47,49,51,55,59,63,65,67,69,71,

%T 75,77,79,83,87,91,95,97,99,101,103,109,111,113,115,119,123,127,129,

%U 131,135,137,139,143,147,151,153,155,159,163,167,169,171,173,175

%N Odd n > 1 such that n+1 is a semiprime times a power of two.

%C Odd n such that n+1 is in A192991.

%C This is to thin numbers A192868 as semiprimes A001358 are to primes A000040.

%F a(n) = A192991(n) - 1.

%e 239 is in the sequence because 239+1 = 240 = 6th semiprime * 2^4 = 3 * 5 * 16.

%Y Cf. A005408, A001358, A192868, A192991.

%K nonn,easy

%O 1,1

%A _Jonathan Vos Post_, Jul 13 2011