You could build something on your own, like:
\documentclass{memoir}
\usepackage{multicol,tikz,xcolor, amsmath}
\usetikzlibrary{calc}
\tikzset{stairwayStyleLineWidth/.style={line width=0.04em}}
\tikzset{stairwayStyleRound/.style={line join=round,line cap=round,stairwayStyleLineWidth}}
\tikzset{stairwayStyleSharp/.style={stairwayStyleLineWidth}}
\tikzset{stairwayStyle/.style={stairwayStyleRound}}
\newcommand{\stairwayup}{\mathbin{
\tikz[baseline=(stairwayanchor.base)]{
\node (stairwayanchor) {\quad};
\draw[stairwayStyle]
($(stairwayanchor.south west) + (0.0em,0.4em)$)
-- ++(0.20em,0) -- ++(0,0.20em)
-- ++(0.20em,0) -- ++(0,0.20em)
-- ++(0.20em,0) -- ++(0,0.20em)
-- ++(0.20em,0) %-- ++(0,0.25em)
;
}}
}
\newcommand{\stairwaydown}{\mathbin{
\tikz[baseline=(stairwayanchor.base)]{
\node (stairwayanchor) {\quad};
\draw[stairwayStyle]
($(stairwayanchor.south east) + (0.0em,0.4em)$)
-- ++(-0.20em,0) -- ++(0,0.20em)
-- ++(-0.20em,0) -- ++(0,0.20em)
-- ++(-0.20em,0) -- ++(0,0.20em)
-- ++(-0.20em,0) %-- ++(0,-0.25em)
;
}}
}
\newcommand{\stairwayupfilled}{\mathbin{
\tikz[baseline=(stairwayanchor.base)]{
\node (stairwayanchor) {\quad};
\draw[stairwayStyle,fill=.]
($(stairwayanchor.south west) + (0.0em,0.4em)$)
-- ++(0,0.20em)
-- ++(0.20em,0) -- ++(0,0.20em)
-- ++(0.20em,0) -- ++(0,0.20em)
-- ++(0.20em,0) %-- ++(0,0.25em)
-- ++(0,-0.60em)
-- cycle
;
}}
}
\newcommand{\stairwayuphollow}{\mathbin{
\tikz[baseline=(stairwayanchor.base)]{
\node (stairwayanchor) {\quad};
\draw[stairwayStyle]
($(stairwayanchor.south west) + (0.0em,0.4em)$)
-- ++(0,0.20em)
-- ++(0.20em,0) -- ++(0,0.20em)
-- ++(0.20em,0) -- ++(0,0.20em)
-- ++(0.20em,0) %-- ++(0,0.25em)
-- ++(0,-0.60em)
-- cycle
;
}}
}
\newcommand{\stairwaydownfilled}{\mathbin{
\tikz[baseline=(stairwayanchor.base)]{
\node (stairwayanchor) {\quad};
\draw[stairwayStyle,fill=.]
($(stairwayanchor.south east) + (0.0em,0.4em)$)
-- ++(0,0.20em)
-- ++(-0.20em,0) -- ++(0,0.20em)
-- ++(-0.20em,0) -- ++(0,0.20em)
-- ++(-0.20em,0) %-- ++(0,-0.25em)
-- ++(0,-0.60em)
-- cycle
;
}}
}
\newcommand{\stairwaydownhollow}{\mathbin{
\tikz[baseline=(stairwayanchor.base)]{
\node (stairwayanchor) {\quad};
\draw[stairwayStyle]
($(stairwayanchor.south east) + (-0.0em,0.4em)$)
-- ++(0,0.20em)
-- ++(-0.20em,0) -- ++(0,0.20em)
-- ++(-0.20em,0) -- ++(0,0.20em)
-- ++(-0.20em,0) %-- ++(0,-0.25em)
-- ++(0,-0.60em)
-- cycle
;
}}
}
\begin{document}
\begin{multicols}{2}
The symbols used in Text $\stairwayupfilled \stairwayup \stairwayuphollow$ and $\stairwaydownfilled \stairwaydown \stairwaydownhollow$ and formulas:
\begin{align*}
&5\stairwayup6 \stairwaydown 7 \\
&\int_{\stairwayup} \omega, \int_{\stairwaydown} \omega\\
&\stairwayupfilled \stairwayup \stairwayuphollow \\
&\stairwaydownfilled \stairwaydown \stairwaydownhollow
\end{align*}
Different sizes and widths:
{\tiny $\stairwayup <$}
{\huge $\stairwayup <$}
\begin{align*}
{\tiny\stairwayup}
{\huge\stairwayup}
\end{align*}
Color:
\begin{align*}
\colorbox{blue}{\color{-blue} $\stairwayupfilled \stairwayup \stairwayuphollow$}
\end{align*}
Normalsize:
\begin{align*}
6 &\stairwayup 5 \stairwaydown 7\\
6 &> 5<7\\
\int_{\stairwayup} & \int_{\stairwaydown}
\end{align*}
\tiny Tiny:
\begin{align*}
6 &\stairwayup 5 \stairwaydown 7\\
6 &> 5<7\\
\int_{\stairwayup} & \int_{\stairwaydown}
\end{align*}
\huge Huge:
\begin{align*}
6 &\stairwayup 5 \stairwaydown 7\\
6 &> 5<7\\
\int_{\stairwayup} & \int_{\stairwaydown}
\end{align*}
\end{multicols}
\end{document}
Observe that the stairs have a round appeal. This way they blend better with <
. You can choose sharp corners if you change
\tikzset{stairwayStyle/.style={stairwayStyleRound}}
to
\tikzset{stairwayStyle/.style={stairwayStyleSharp}}
if you want to. The thickness of the strokes varies with the font size and the symbols do change their color appropriately.
Tikz is very versatile once you have a basic understanding. It might be relatively slow compared to other low level software, though. My code might have some room for improvement.