OFFSET
1,2
COMMENTS
See triangle A133568: Each row gives the least sequence of n positive integers such that a(n) distinct numbers are generated by these operations. - Rick L. Shepherd, Sep 16 2007
LINKS
Alois P. Heinz, Table of n, a(n) for n = 1..300
Mikelis Emils Mikelsons, List of expressions for a(5)
FORMULA
a(n) = Sum_{i=1..n} binomial(n,i)*A140606(i). - Mikelis Emils Mikelsons, Sep 01 2021
EXAMPLE
a(2) = 8 : from two variables x and y we obtain the eight functions x, y, x+y, x*y, x-y, y-x, x/y and y/x.
CROSSREFS
KEYWORD
nonn
AUTHOR
Daniel Rainjonneau (d.rainjonneau(AT)wanadoo.fr), Sep 11 2007
EXTENSIONS
Definition corrected by Rick L. Shepherd, Sep 16 2007
a(5)-a(17) from Mikelis Emils Mikelsons, Sep 01 2021
STATUS
approved