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A048274 Let G be the graph with n vertices, the i-th vertex consisting of all multiples of i <= n, where edges indicate that the vertices intersect; a(n) = |n-(number of edges of G)|. 1

%I

%S 1,1,1,0,0,3,3,5,6,9,9,15,15,18,21,24,24,30,30,36,39,42,42,51,52,55,

%T 57,63,63,75,75,79,82,85,88,99,99,102,105,114,114,126,126,132,138,141,

%U 141,153,154,160,163,169,169,178,181,190,193,196,196,217,217,220,226

%N Let G be the graph with n vertices, the i-th vertex consisting of all multiples of i <= n, where edges indicate that the vertices intersect; a(n) = |n-(number of edges of G)|.

%e For n=6 the vertices are {1,2,3,4,5,6},{2,4,6},{3,6},{4},{5},{6}. There are 9 = 5+3+1 edges and so a(6) = |6-9| = 3.

%K nonn

%O 1,6

%A _Stephen P. Humphries_

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Last modified September 20 07:22 EDT 2021. Contains 347577 sequences. (Running on oeis4.)