A238951 The number of arcs from odd to even level vertices in divisor lattice D(n).

0, 0, 0, 1, 0, 2, 0, 1, 1, 2, 0, 3, 0, 2, 2, 2, 0, 3, 0, 3, 2, 2, 0, 5, 1, 2, 1, 3, 0, 6, 0, 2, 2, 2, 2, 6, 0, 2, 2, 5, 0, 6, 0, 3, 3, 2, 0, 6, 1, 3, 2, 3, 0, 5, 2, 5, 2, 2, 0, 10, 0, 2, 3, 3, 2, 6, 0, 3, 2, 6, 0, 8, 0, 2, 3, 3, 2, 6, 0, 6, 2, 2, 0, 10, 2, 2

Offset

1,6

Links

R. J. Mathar, Table of n, a(n) for n = 1..1000

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 (see 12th line in Table 1).

Formula

a(n) = A062799(n) - A238950(n) = floor(A062799(n)/2). [Cha eqs. (2.34), (2.37)]

Maple

read("transforms"):
omega := [seq(A001221(n), n=1..1000)] ;
ones := [seq(1, n=1..1000)] ;
a062799 := DIRICHLET(ones, omega) ;
for n from 1 do
    a238951 := floor(op(n, a062799)/2) ;
    printf("%d %d\n", n, a238951) ;
end do: # R. J. Mathar, May 28 2017

Crossrefs

Cf. A056924, A062799, A238950.

Sequence in context: A329747 A304455 A345354 * A071466 A155041 A334296

Adjacent sequences: A238948 A238949 A238950 * A238952 A238953 A238954

Keyword

nonn

Author

Sung-Hyuk Cha, Mar 07 2014

Status

approved