This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A075593 #7 Dec 05 2013 19:55:38 %S A075593 1,3,4,2,9,5,6,19,10,11,8,7,12,13,16,17,14,31,22,23,18,37,24,41,20,29, %T A075593 30,47,26,43,28,53,36,59,38,61,40,71,32,67,34,83,44,73,54,79,48,97,42, %U A075593 101,50,103,46,89,60,109,58,107,56,113,66,137,62,127,52,131,68,139,72 %N A075593 a(1) = 1, a(2n) = prime, a(2n+1) = composite and sum of two successive terms is alternately composite or prime. %C A075593 This is not a permutation of the positive integers; odd composites > 9 will not appear in the sequence. - _Klaus Brockhaus_, Feb 06 2006 %Y A075593 Cf. A075594, A103824, A103825. %K A075593 nonn %O A075593 1,2 %A A075593 _Amarnath Murthy_, Sep 27 2002 %E A075593 Extended by _Ray Chandler_ Feb 16 2005