Solution:
Yes, there are infinitely many such rows. For example,
(68203)=2(67203) and (85203)=2(83203)
There are infinitely many rows having two adjacent elements in a 1:2 ratio, for
2(kn)=(k+1n)
reduces to 2(k+1)=n−k, or n=3k+2. So as long as n≡2(mod3), there will be two adjacent elements in a 1:2 ratio.
Next, we search for "doubles" that are not adjacent. The next easiest case to try is
2(kn)=(k+2n)
which reduces to
2(k+2)(k+1)=(n−k)(n−k−1).
Substitute u=n−k and v=k+2; our equation becomes
2(v2−v)=u2−u
Multiplying both sides by 4 and completing the square yields
2(4v2−4v+1)=4u2−4u+1+1,
so substituting x=2v−1, y=2u−1 reduces the original equation to
2x2−y2=1.
This is a Pell's equation with infinitely many solutions which can be generated in the standard way, or we can observe that (1,1), (5,7) are solutions and that if (x,y) is a solution, then (3x+2y,4x+3y) is also a solution.
It remains to show that one of these solutions produces an n which is congruent to 2 modulo 3. Since n=2x+y−1, we must have x+y≡0(mod6). The first solution with this property is (5,7), but this doesn't work, because it corresponds to n=5, and the elements of the row are 1,5,10,10,5,1, so the doubles are not distinct. Generating solutions via (x,y)→(3x+2y,4x+3y) modulo 6, we have the repeating pattern
(1,1),(−1,1),(−1,−1),(1,−1),(1,1),…
which shows that every other solution (x,y) has the property x+y≡0(mod6). The next solution after (5,7) with this property will correspond to an n large enough so that the doubles will be distinct. Specifically, the solution is (169,239) which corresponds to n=203, k=83.