\documentclass[a4paper,portrait]{article}
\usepackage{pdfpages}
\usepackage{multido}
\begin{document}
\includepdf[landscape,angle=-90,pages=1,fitpaper=true,trim=0 0 0 0,offset=0 0,turn=true,noautoscale=false]{appunti-blu-orig.pdf}
\includepdf[landscape,pages=-,fitpaper=true,trim=0 0 0 0,offset=0
0,turn=true,noautoscale=false]{indice.pdf}
\includepdf[landscape,angle=-90,pages=2,fitpaper=true,trim=0 0 0 0,offset=0 0,turn=true,noautoscale=false]{appunti-blu-orig.pdf}
\includepdf[landscape,angle=-90,pages=-,fitpaper=true,trim=0 0 0 0,offset=0
0,turn=true,noautoscale=false]{appunti-blu-pagina2.pdf}
%\includepdf[landscape,angle=-90,pages=3,fitpaper=true,trim=0 0 0 0,offset=0 0,turn=true,noautoscale=false]{appunti-blu-orig.pdf}

\multido{\i=4+2}{18}{
\includepdf[landscape,angle=90,pages=\i,fitpaper=true,trim=0 0 0 0,offset=0 0,turn=true,noautoscale=false]{appunti-blu-orig.pdf}
\FPadd{\i}{1}{\ii}
\includepdf[landscape,angle=-90,pages=\ii,fitpaper=true,trim=0 0 0 0,offset=0 0,turn=true,noautoscale=false]{appunti-blu-orig.pdf}
}

\includepdf[pages=-,fitpaper=true,trim=0 0 0 0,offset=0
0,turn=true,noautoscale=false]{Phi-tabella.pdf}
\end{document}
\end{document}