Looking at prime multiples of $P=[1,1]$ on the curve $y^2=x^3+x-1$ the size of the denominator grows quite rapidly. So $5P=[\frac{685}{11^2},\frac{-18157}{11^3}],7P=[\frac{[154513}{443^2},\frac{-45623219}{443^3}]$
Looking purely at the x coordinate we have
k sqrt(denominator(k*P))
3 1
5 11
7 443
11 656243
13 1048516201
17 4451192987631289
19 429330677071423079
23 77700648618312971843469771251
29 7517777790273327975717181745948599636777678033
31 30820930821843565941522654527823658160891296876267921
37 587308602722146793206557071567309610618121704728654635117962467133627539771
41 22916712844996907328126003624983339852284728578820686400041407536873657173496053280584200979
I know this involves the Neron-Tate height somehow and is part of the reason finding a factor-base for calculating discrete logs on elliptic curves over $F_p$ seems impossible.
I was wondering if there is a choice of point or curve or prime multiple for which the size of the denominator of large prime multiples of that point would be small, or at least a partial factorization could be achieved.
Is this possible?
It would be very interesting to find a large composite number $n$ which could be shown to be a factor of the denominator of a a roughly $n^\frac13$-sized prime multiple of a point.