%I
%S 1,3,5,7,7,9,11,9,11,13,15,9,11,13,15,15,11,13,15,17,17,19,13,15,17,
%T 19,19,21,23,11,13,15,17,17,19,21,19,13,15,17,19,19,21,23,21,23,15,17,
%U 19,21,21,23,25,23,25,27,17,19,21,23,23,25,27,25,27,29,31,11,13,15,17,17
%N List pairs (i,j) with 1 <= i <= j in lexicographic order: (1,1), (1,2), (2,2), (1,3), (2,3), (3,3), (1,4), ... Let a(1) = 1. Then for n>=2 if the (n1)st pair is (i,j) then a(n) = a(i) + a(j) + 1.
%C All entries are odd. There are A001190(n) occurrences of 2n1 in this sequence
%e a(2) = a(1)+a(1)+1 = 3, a(3) = a(1)+a(2)+1 = 5, a(4) = a(2)+a(2)+1 = 7, a(5) = a(1)+a(3)+1 = 7, ...
%K easy,nonn
%O 1,2
%A Claude Lenormand (claude.lenormand(AT)free.fr), Sep 14 2001
