OFFSET
1,5
FORMULA
a(n) = Sum_{k=1..floor(n/3)} Sum_{i=k..floor((n-k)/2)} sign(floor(1/gcd(i,k)) + floor(1/gcd(i,n-i-k))).
MATHEMATICA
Table[Sum[Sum[Sign[Floor[1/GCD[k, i]] + Floor[1/GCD[i, 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