A103934 - cp's OEIS frontend

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.

%I A103934 #5 Jul 09 2025 04:24:38
%S A103934 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 A103934 49,43,119,47,51,53,91,59,77,61,125,67,143,71,69,73,65,79,63,83,75,89,
%U A103934 121,97,81,101,99,103,87,107,117,109,135,113,93,127,111,131,129,137,115,139
%N 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.
%Y A103934 Cf. A075593, A075594, A103824, A103825, A103935.
%K A103934 nonn
%O A103934 1,2
%A A103934 _Ray Chandler_ Feb 21 2005, based on a suggestion from Zak Seidov

cp's OEIS Frontend

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.