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a(n) is the smallest number that is not less than n such that n*a(n)+2 is semiprime.
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%I #10 Oct 08 2020 20:05:52

%S 2,2,4,5,11,6,7,9,13,12,11,12,19,16,19,17,17,18,20,21,23,30,24,26,32,

%T 34,27,30,29,36,37,36,35,36,35,41,37,40,43,41,43,42,43,45,47,50,48,48,

%U 51,52,51,57,53,54,55,57,59,60,61,60,63,76,64,65,65,66,75

%N a(n) is the smallest number that is not less than n such that n*a(n)+2 is semiprime.

%C Motivated by a question about arranging square tiles in a rectangle.

%Y Cf. A001358, A338049.

%K nonn

%O 1,1

%A _N. J. A. Sloane_, Oct 08 2020, based on an email from _Todor Szimeonov_, Oct 07 2020