

A048274


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


1



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, 57, 63, 63, 75, 75, 79, 82, 85, 88, 99, 99, 102, 105, 114, 114, 126, 126, 132, 138, 141, 141, 153, 154, 160, 163, 169, 169, 178, 181, 190, 193, 196, 196, 217, 217, 220, 226
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OFFSET

1,6


LINKS

Table of n, a(n) for n=1..63.


EXAMPLE

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) = 69 = 3.


CROSSREFS

Sequence in context: A011976 A060022 A187679 * A059892 A241090 A091607
Adjacent sequences: A048271 A048272 A048273 * A048275 A048276 A048277


KEYWORD

nonn


AUTHOR

Stephen P. Humphries


STATUS

approved



