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\leftline{Slavik V. Jablan}
\leftline{Matemati\v{c}ki Institut SANU}
\leftline{Kneza Mihaila 36}
\leftline{11001 Beograd, p.p. 367}
\line{SERBIA\hfil 31 August 2009}
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Dear Dr. Jablan,

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\def\\#1{{\j#1\kern.5em}}
Yesterday I amused myself by using {\logo METAFONT} to make a font
based on one of your modular tiles.
The font has your four characters, `\\0', `\\1', `\\2', and `\\3';
I also added two experimental ones with a neutral center,
`\\4' and `\\5'. With this font \TeX\ can, for example, easily produce
$$\vcenter{\j\hsize=14em\offinterlineskip\obeylines
..4.4.4.4.4.4.4.4.4.4.4.4.4.
.523030323232545454545454545
.523032121212545454545454545
.523012121212303032323032545
.523012123010321232121032545
.543230303232321212121032545
.545230321212121212103032545
.545230121212123030323230325
.545230121230103212321210325
.545434343434343212121210325
.545454545454545212121030325
.545454545454545434343434345
%.5.5.5.5.5.5.5.5.5.5.5.5.5.5
}\qquad\vcenter{\halign{\hfil#\hfil\cr as well as\cr your original\cr}}\qquad
\vcenter{\j\hsize=14em\offinterlineskip\obeylines
23030323232...............
23032121212...............
23012121212303032323032...
23012123010321232121032...
.3230303232321212121032...
..230321212121212103032...
..23012121212303032323032.
..23012123010321232121032.
...3.3.3.3.3.321212121032.
..............21212103032.
...............3.3.3.3.3..
}$$

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Would you object if I make the source code for this font
freely available on my website and on the CTAN archive for
\TeX\ users? Of course I would credit you for the idea.

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\rightline{\vbox{\halign{#\hfil\cr
                 Sincerely,\cr
                 \noalign{\vskip30pt}
                 Donald E. Knuth\cr
                 Professor Emeritus of The Art of Computer Programming\cr}}}
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