OFFSET
1,5
FORMULA
a(n) = Sum_{k=1..floor(n/3)} Sum_{i=k..floor((n-k)/2)} floor(1/gcd(k,i)) * floor(1/gcd(k,n-i-k)).
MATHEMATICA
Table[Sum[Sum[Floor[1/GCD[k, i]]*Floor[1/GCD[k, n - i - k]], {i, k, Floor[(n - k)/2]}], {k, Floor[n/3]}], {n, 80}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Wesley Ivan Hurt, Jan 02 2021
STATUS
approved