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%I #14 May 26 2015 09:57:15
%S 1,2,1,4,5,2,5,4,1,6,9,4,13,14,5,12,9,2,9,12,5,14,13,4,9,6,1,8,13,6,
%T 21,24,9,22,17,4,21,30,13,40,41,14,33,24,5,22,29,12,33,30,9,20,13,2,
%U 13,20,9,30,33,12,29,22,5,24,33,14,41,40,13,30,21,4,17,22,9,24,21,6,13,8,1,10
%N Expansion of product(n>=0, 1+2*x^(3^n)+x^(2*3^n)+2*x^(3*3^n)+x^(4*3^n) ).
%C This is an analog of the classical Stern sequence (A002487) with generating function product(n>=0, 1+x^(2^n)+x^(2*2^n) ).
%C The author of the linked paper proves that the sequence {a(n)/a(n+1)} enumerates the set of positive rational numbers with either an even numerator or an even denominator.
%H Song Heng Chan, <a href="http://www.emis.de/journals/INTEGERS/papers/l26/l26.Abstract.html">Analogs of the Stern Sequence</a>,INTEGERS 11(2011) #A26 (10 pages).
%Y Cf. A002487.
%K nonn
%O 0,2
%A _John W. Layman_, Jun 01 2011
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