OFFSET
1,5
LINKS
Alois P. Heinz, Table of n, a(n) for n = 1..1000
EXAMPLE
a(4) = 0 because there is only one ordered quadruple of distinct positive integers with largest element 4, (1,2,3,4), but the elements are not pairwise coprime, 2 and 4 have a common factor >1.
a(8) = 4 because there are only four ordered quadruples of distinct pairwise coprime positive integers with largest element 8: (1,3,5,8), (1,3,7,8), (1,5,7,8), (3,5,7,8).
CROSSREFS
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Feb 15 2011
STATUS
approved