cp's OEIS Frontend

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

%I A238951 #26 May 21 2025 22:02:47
%S A238951 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,
%T A238951 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,
%U A238951 2,6,0,8,0,2,3,3,2,6,0,6,2,2,0,10,2,2
%N A238951 The number of arcs from odd to even level vertices in divisor lattice D(n).
%H A238951 R. J. Mathar, <a href="/A238951/b238951.txt">Table of n, a(n) for n = 1..1000</a>
%H A238951 Sung-Hyuk 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 (see 12th line in Table 1).
%F A238951 a(n) = A062799(n) - A238950(n) = floor(A062799(n)/2). [Cha eqs. (2.34), (2.37)]
%F A238951 a(n) = (A062799(n) - A358769(n))/2. - _Ridouane Oudra_, May 17 2025
%p A238951 read("transforms"):
%p A238951 omega := [seq(A001221(n), n=1..1000)] ;
%p A238951 ones := [seq(1,n=1..1000)] ;
%p A238951 a062799 := DIRICHLET(ones,omega) ;
%p A238951 for n from 1 do
%p A238951     a238951 := floor(op(n,a062799)/2) ;
%p A238951     printf("%d %d\n",n,a238951) ;
%p A238951 end do: # _R. J. Mathar_, May 28 2017
%Y A238951 Cf. A056924, A062799, A238950, A358769.
%K A238951 nonn
%O A238951 1,6
%A A238951 _Sung-Hyuk Cha_, Mar 07 2014