A238960 The number of arcs from odd to even level vertices in divisor lattice in graded colexicographic order.

0, 0, 1, 2, 1, 3, 6, 2, 5, 6, 10, 16, 2, 6, 8, 14, 16, 26, 40, 3, 8, 11, 12, 18, 23, 27, 36, 42, 64, 96, 3, 9, 13, 15, 22, 29, 32, 37, 46, 58, 67, 88, 102, 152, 224, 4, 11, 16, 19, 20, 26, 36, 41, 48, 52, 56, 74, 80, 93, 108, 112, 140, 162, 208, 240, 352, 512

Offset: 0

Author

Sung-Hyuk Cha, Mar 07 2014

Keywords

• nonn
• tabf

Examples

			Triangle T(n,k) begins:
  0;
  0;
  1, 2;
  1, 3,  6;
  2, 5,  6, 10, 16;
  2, 6,  8, 14, 16, 26, 40;
  3, 8, 11, 12, 18, 23, 27, 36, 42, 64, 96;
  ...
		

Links

• Andrew Howroyd, Table of n, a(n) for n = 0..2713 (rows 0..20)
• S.-H. Cha, E. G. DuCasse, and L. V. Quintas, Graph Invariants Based on the Divides Relation and Ordered by Prime Signatures, arXiv:1405.5283 [math.NT], 2014, Table A.1 entry |E_O(S)|.

Crossrefs

Cf. A238951 in graded colexicographic order.

Cf. A036035, A238953, A238959, A238973.

Formula

T(n,k) = A238951(A036035(n,k)).

From Andrew Howroyd, Apr 25 2020: (Start)

T(n,k) = floor(A238953(n,k)/2).

T(n,k) = A238953(n,k) - A238959(n,k). (End)

Extensions

Offset changed and terms a(50) and beyond from Andrew Howroyd, Apr 25 2020