OFFSET
1,5
FORMULA
a(n) = Sum_{k=1..floor(n/3)} Sum_{i=k..floor((n-k)/2)} sign(floor(1/gcd(n-i-k,k)) + floor(1/gcd(n-i-k,i))).
MATHEMATICA
Table[Sum[Sum[Sign[Floor[1/GCD[n - i - k, k]] + Floor[1/GCD[n - i - k, i]]], {i, k, Floor[(n - k)/2]}], {k, Floor[n/3]}], {n, 80}]
lppQ[{a_, b_, c_}]:=Total[Boole[{CoprimeQ[c, a], CoprimeQ[b, a]}]]>0; Table[Length[ Select[ IntegerPartitions[n, {3}], lppQ]], {n, 70}] (* Harvey P. Dale, May 08 2022 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Wesley Ivan Hurt, Jan 02 2021
STATUS
approved