In an automatic vertical stacking of a certain subsequent number span - how to regulate spacing between those numbers?

Question

On the StackExchange-chat, I received quickly-made MWE's which answered parts of my question; yet remarkably show the experience and knowledge of the person who fabricated them.

For example, when I asked how to create a code which would automatically right-align a vertically stacked series of numbers (from 2 to 50), I got the following answers, which worked perfectly:

Answer 1:

\documentclass{article}

\newcounter{loopcounter}

\begin{document}
\setcounter{loopcounter}{50}
\loop\unless\ifnum\value{loopcounter}=1
\llap{\theloopcounter}
\addtocounter{loopcounter}{-1}
\repeat

\end{document}

Answer 2:

\documentclass{article}

\newcounter{loopcounter}

\makeatletter
\newcommand{\loopdown}[2]{%
\c@loopcounter=#1%
\loop\unless\ifnum\value{loopcounter}=#2
\llap{\theloopcounter}%
\advance \c@loopcounter by -1
\repeat
}
\makeatother

\begin{document}
\loopdown{50}{1}
\end{document}

What I am wondering about, is how to regulate the vertical spacing between the different lines of numbers? In other words: the line-spacing.

Answer 1

A recursive stack (\fbox thrown in for flair [easily removed]). Note also the stack spacing has no effect on the underlying line spacing of the document.

\documentclass{article}
\usepackage{stackengine}
\newcounter{loopcounter}
\newcommand\makestack[3]{%
  \def\currentstack{#2}%
  \setcounter{loopcounter}{\the\numexpr#2-1\relax}%
  \loop\unless\ifnum\value{loopcounter}=\numexpr#3-1\relax%
  \savestack{\currentstack}{\stackengine{#1}{\currentstack}{\theloopcounter}%
    {U}{r}{F}{F}{S}}%
  \addtocounter{loopcounter}{-1}%
  \repeat%
  \fbox{\currentstack}%
}
\begin{document}
\makestack{2pt}{50}{2}%
 x%
\makestack{1pt}{50}{2}%
 x%
\makestack{.5pt}{50}{2}%
 x%
\makestack{.5pt}{47}{11}%
\end{document}

If one wants the spacing to be the inter-baselineskip, rather than the inter-character vertical gap, then this:

\documentclass{article}
\usepackage{stackengine}
\newcounter{loopcounter}
\newcommand\makestack[3]{%
  \def\currentstack{#2}%
  \setcounter{loopcounter}{\the\numexpr#2-1\relax}%
  \loop\unless\ifnum\value{loopcounter}=\numexpr#3-1\relax%
  \savestack{\currentstack}{\stackengine{#1}{\theloopcounter}{\currentstack}%
    {O}{r}{F}{F}{L}}%
  \addtocounter{loopcounter}{-1}%
  \repeat%
  \fbox{\currentstack}%
}
\begin{document}
\makestack{9pt}{50}{2}%
 x%
\makestack{8.5pt}{50}{2}%
 x%
\makestack{8pt}{50}{2}%
 x%
\makestack{8pt}{47}{11}%
\end{document}

Answer 2

I can suggest a key-value interface:

\documentclass{article}
\usepackage{xparse}

\ExplSyntaxOn

\keys_define:nn { vincent/printnumbers }
 {
  start .int_set:N = \l_vincent_printnumbers_start_int,
  step  .int_set:N = \l_vincent_printnumbers_step_int,
  end   .int_set:N = \l_vincent_printnumbers_end_int,
  wrapper .tl_set:N = \l_vincent_printnumbers_wrapper_tl,
  sep .tl_set:N = \l_vincent_printnumbers_sep_tl,
  start .value_required:n = true,
  step .value_required:n = true,
  end .value_required:n = true,
  wrapper .initial:n = \use:n,
  sep .initial:n = {,~},
 }

\NewDocumentCommand{\printnumbers}{m}
 {
  \group_begin:
  \keys_set:nn { vincent/printnumbers } { #1 }
  \seq_clear:N \l_vincent_printnumbers_seq
  \int_step_inline:nnnn
   { \l_vincent_printnumbers_start_int }
   { \l_vincent_printnumbers_step_int }
   { \l_vincent_printnumbers_end_int }
   {
    \seq_put_right:Nx \l_vincent_printnumbers_seq
     {
      \exp_not:V \l_vincent_printnumbers_wrapper_tl { ##1 }
     }
   }
  \seq_use:Nn \l_vincent_printnumbers_seq { \l_vincent_printnumbers_sep_tl }
  \group_end:
 }
\ExplSyntaxOff

\begin{document}

\noindent\printnumbers{
  start=20,
  end=2,
  step=-1,
  wrapper=\makebox[1em][r],
  sep=\\[10pt],
}

\noindent\printnumbers{
  start=1,end=30,step=4,
}
\end{document}