OFFSET
1,4
COMMENTS
Row 3n is given by 2n*(1,2,3,4,5,6,...).
LINKS
G. C. Greubel, Table of n, a(n) for the first 50 rows, flattened
FORMULA
R(m,n) = floor((2*m*n + 1)/3) if n == 1 (mod 3) and floor(2*m*n/3) otherwise.
MAPLE
A := proc(n, k) ## n = 0 .. infinity and k = 0 .. n
if 1 = (n-k+1) mod 3 then
floor((2*(k+1)*(n-k+1)+1) / 3)
else
floor((2*(k+1)*(n-k+1)) / 3)
end if
end proc: # Yu-Sheng Chang, Jan 01 2020
MATHEMATICA
b[n_, m_] := If[Mod[n, 3] == 1, Floor[(2*m*n + 1)/3], Floor[2*m*n/3]]; a:= Table[a[n, m], {n, 1, 25}, {m, 1, 25}]; Table[a[[k, n - k + 1]], {n, 1, 20}, {k, 1, n}]//Flatten (* G. C. Greubel, Dec 05 2017 *)
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
Clark Kimberling, Sep 07 2008
STATUS
approved