OFFSET
0,3
COMMENTS
A primitive set has no element that divides another element in the same set.
REFERENCES
R. K. Guy, Unsolved Problems in Number Theory, Springer-Verlag, New York, (1994).
LINKS
Fausto A. C. Cariboni, Table of n, a(n) for n = 0..75
Eric Weisstein's World of Mathematics, Primitive Sequence.
FORMULA
a(n) = Sum_{k=1..ceiling(n/2)} k * A355145(n,k). - Alois P. Heinz, Jun 27 2022
EXAMPLE
a(4)=8 since the primitive subsets of (1,2,3,4) are ( ) (1) (2) (3) (4) (2,3) (3,4) and these contain eight elements
CROSSREFS
KEYWORD
nonn
AUTHOR
Alan Sutcliffe (alansut(AT)ntlworld.com), Aug 10 2003
EXTENSIONS
Terms a(34)-a(37) from Fausto A. C. Cariboni, Feb 02 2022
STATUS
approved