OFFSET
1,6
FORMULA
a(n) = Sum_{j=1..floor(n/3)} Sum_{i=j..floor((n-j)/2)} (ceiling(i*j/(i+j)) - floor(i*j/(i+j))) * (ceiling((i*(n-i-j))/(n-j)) - floor(i*(n-i-j)/(n-j))) * (ceiling((j*(n-i-j))/(n-i)) - floor(j*(n-i-j)/(n-i))).
MATHEMATICA
Table[Sum[Sum[(Ceiling[i*j/(i + j)] - Floor[i*j/(i + j)]) (Ceiling[(i*(n - i - j))/(n - j)] - Floor[i*(n - i - j)/(n - j)]) (Ceiling[(j*(n - i - j))/(n - i)] - Floor[j*(n - i - j)/(n - i)]), {i, j, Floor[(n - j)/2]}], {j, Floor[n/3]}], {n, 100}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Wesley Ivan Hurt, Apr 05 2021
STATUS
approved