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A238973
The number of arcs from odd to even level vertices in divisor lattice in canonical order.
3
0, 0, 1, 2, 1, 3, 6, 2, 5, 6, 10, 16, 2, 6, 8, 14, 16, 26, 40, 3, 8, 11, 18, 12, 23, 36, 27, 42, 64, 96, 3, 9, 13, 22, 15, 29, 46, 32, 37, 58, 88, 67, 102, 152, 224, 4, 11, 16, 26, 19, 36, 56, 20, 41, 48, 74, 112, 52, 80, 93, 140, 208, 108, 162, 240, 352, 512
OFFSET
0,4
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.
FORMULA
From Andrew Howroyd, Mar 28 2020: (Start)
T(n,k) = A238951(A063008(n,k)).
T(n,k) = A238964(n,k) - A238972(n,k).
T(n,k) = floor(A238964(n,k)/2). (End)
EXAMPLE
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, 18, 12, 23, 36, 27, 42, 64, 96;
...
CROSSREFS
Cf. A238960 in canonical order.
Sequence in context: A213935 A106578 A238960 * A335444 A358646 A006895
KEYWORD
nonn,tabf
AUTHOR
Sung-Hyuk Cha, Mar 07 2014
EXTENSIONS
Offset changed and terms a(50) and beyond from Andrew Howroyd, Mar 28 2020
STATUS
approved