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A103934 Choose a(n) to be the smallest odd number not yet used such that: a(1) = 1, a(2n) = prime, a(2n+1) = composite and partial sums are alternately composite or prime. 1

%I

%S 1,3,9,5,25,7,21,11,15,13,27,17,39,19,45,23,33,29,55,31,35,37,57,41,

%T 49,43,119,47,51,53,91,59,77,61,125,67,143,71,69,73,65,79,63,83,75,89,

%U 121,97,81,101,99,103,87,107,117,109,135,113,93,127,111,131,129,137,115,139

%N Choose a(n) to be the smallest odd number not yet used such that: a(1) = 1, a(2n) = prime, a(2n+1) = composite and partial sums are alternately composite or prime.

%Y Cf. A075593, A075594, A103824, A103825, A103935.

%K nonn

%O 1,2

%A _Ray Chandler_ Feb 21 2005, based on a suggestion from Zak Seidov.

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Last modified May 6 06:00 EDT 2021. Contains 343580 sequences. (Running on oeis4.)