OFFSET
1,1
COMMENTS
A184920: 7,15,24,31,40,48,55,64,...
A184921: 3,8,13,18,23,27,32,37,...
A184922: 2,5,9,12,16,19,22,26,29,...
A184923: 1,4,6,10,11,14,17,20,21,...
Jointly rank the sets {h*r}, {i*s}, {j*t}, {k*u},
where h>=1, i>=1, j>=1, k>=1. The position of n*s in the joint ranking is n+[rn/s]+[tn/s]+[un/s], and likewise for the positions of n*r, n*t, and n*u.
MATHEMATICA
r=2^(1/2); s=r+1; t=r+2; u=r+3);
a[n_]:=n+Floor[n*s/r]+Floor[n*t/r]+Floor[n*u/r];
b[n_]:=n+Floor[n*r/s]+Floor[n*t/s]+Floor[n*u/s];
c[n_]:=n+Floor[n*r/t]+Floor[n*s/t]+Floor[n*u/t];
d[n_]:=n+Floor[n*r/u]+Floor[n*s/u]+Floor[n*t/u];
Table[a[n], {n, 1, 120}] (* A184920 *)
Table[b[n], {n, 1, 120}] (* A184921 *)
Table[c[n], {n, 1, 120}] (* A184922 *)
Table[d[n], {n, 1, 120}] (* A184923 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Clark Kimberling, Jan 26 2011
STATUS
approved