OFFSET
1,6
FORMULA
T(a, b) = (a*b-a-b+gcd(a,b))/2.
T(n, n) = n*(n-1)/2.
EXAMPLE
0;
0 1;
0 1 3;
0 2 3 6;
0 2 4 6 10;
0 3 6 8 10 15;
0 3 6 9 12 15 21;
0 4 7 12 14 18 21 28;
0 4 9 12 16 21 24 28 36;
0 5 9 14 20 23 27 32 36 45;
MATHEMATICA
Table[Sum[Floor[(k b)/a], {k, a-1}], {a, 20}, {b, a}] // Flatten
CROSSREFS
KEYWORD
AUTHOR
Jaimal Ichharam, Jul 15 2014
STATUS
approved