

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
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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.
Cf. A063008, A238951, A238964, A238972.
Sequence in context: A213935 A106578 A238960 * A335444 A006895 A202204
Adjacent sequences: A238970 A238971 A238972 * A238974 A238975 A238976


KEYWORD

nonn,tabf


AUTHOR

SungHyuk Cha, Mar 07 2014


EXTENSIONS

Offset changed and terms a(50) and beyond from Andrew Howroyd, Mar 28 2020


STATUS

approved



