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%I #18 Apr 25 2020 18:13:19
%S 0,1,1,2,2,4,6,2,5,6,10,16,3,7,9,14,17,26,40,3,8,11,12,18,23,27,36,42,
%T 64,96,4,10,14,16,22,30,32,38,46,58,68,88,102,152,224,4,11,16,19,20,
%U 26,36,41,48,52,56,74,80,93,108,112,140,162,208,240,352,512
%N The number of arcs from even to odd level vertices in divisor lattice in graded colexicographic order.
%H Andrew Howroyd, <a href="/A238959/b238959.txt">Table of n, a(n) for n = 0..2713</a> (rows 0..20)
%H S.-H. Cha, E. G. DuCasse, and L. V. Quintas, <a href="http://arxiv.org/abs/1405.5283">Graph Invariants Based on the Divides Relation and Ordered by Prime Signatures</a>, arxiv:1405.5283 [math.NT], 2014.
%F T(n,k) = A238950(A036035(n,k)).
%F From _Andrew Howroyd_, Apr 25 2020: (Start)
%F T(n,k) = ceiling(A238953(n,k)/2).
%F T(n,k) = A238953(n,k) - A238960(n,k). (End)
%e Triangle T(n,k) begins:
%e 0;
%e 1;
%e 1, 2;
%e 2, 4, 6;
%e 2, 5, 6, 10, 16;
%e 3, 7, 9, 14, 17, 26, 40;
%e 3, 8, 11, 12, 18, 23, 27, 36, 42, 64, 96;
%e ...
%Y Cf. A238950 in graded colexicographic order.
%Y Cf. A036035, A238953, A238960, A238972.
%K nonn,tabf
%O 0,4
%A _Sung-Hyuk Cha_, Mar 07 2014
%E Offset changed and terms a(50) and beyond from _Andrew Howroyd_, Apr 25 2020
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