OFFSET
1,2
COMMENTS
Joint-rank arrays are defined in the first comment at A182801.
FORMULA
T(i,j)=sum(k>=1, floor( j*(i-1+r)/(k-1+r) ) ) where r=sqrt(3), for i>=1, j>=1.
EXAMPLE
Northwest corner:
1....3....6...10...
2....7...13...20...
4...11...21...32...
5...16...30...44...
MATHEMATICA
r=Sqrt[3];
f[i_, j_]:=Sum[Floor[j*(i-1+r)/(k-1+r)], {k, 1, 1+r+j(i-1+r)}];
TableForm[Table[f[i, j], {i, 1, 10}, {j, 1, 10}]]
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
Clark Kimberling, Dec 08 2010
STATUS
approved