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Choose a(n) to be the smallest odd number not yet used such that: a(1) = 1, a(2n) = composite, a(2n+1) = prime and partial sums are alternately composite or prime.
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%I #3 Mar 30 2012 17:29:22

%S 1,9,3,15,13,21,5,25,11,27,7,33,23,35,29,39,17,45,31,49,19,51,61,55,

%T 37,57,43,63,53,65,41,69,71,75,79,77,73,81,59,85,47,87,103,91,83,93,

%U 113,95,109,99,127,105,149,111,139,115,89,117,107,119,97,121,131,123,67,125

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

%Y Cf. A075593, A075594, A103824, A103825, A103934.

%K nonn

%O 1,2

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